There is little or no evidence supporting any part of Steiner's "spiritual science." From time to time Steiner tried to offer some evidence, but the effort was futile. There can be no real evidence proving the truth of fantasies. Here's an example. Steiner repeatedly referred to experiments with divining rods that, he argued, gave at least tangential evidence for his teachings.* Problem: Genuine experiments have done nothing of the sort. Divining rods are bogus.

A divining rod is a magical tool for finding water or other substances underground. The use of such gimcracks is called dowsing. (Many dowsers dislike the term “divining”; they claim their work is rational and scientific. This is similar to the claim Steiner made for his own “investigations.” But neither dowsing nor Anthroposophy is rational or scientific, and neither provides evidence for the other.) 

Here is the ENCYCLOPÆDIA BRITANNICA's 

entire article on dowsing: 

"dowsing: in occultism, use of a forked piece of hazel, rowan, or willow wood or of a Y-shaped metal rod or of a pendulum suspended by a nylon or silk thread, in an attempt to detect such hidden substances as water, minerals, treasure, archaeological remains, and even dead bodies. The practice seems to have first come into vogue in the European Middle Ages.

"The dowser in his search grasps the rod (itself called a dowser) by its two prongs and appears to receive transmissions from the hidden object that cause involuntary muscular contractions, which in turn make the rod bend or quiver violently. Some dowsers claim to be able to detect buried substances merely by passing a dowsing rod over a map of the area where the substance lies hidden. The term divining rod, sometimes used to describe the forked instrument, is frowned upon by dowsers because divination is not considered part of the process." — "dowsing." ENCYCLOPÆDIA BRITANNICA, Online, 09 Feb. 2010.

And here is Steiner on the same subject. Steiner accepts the utility of divining rods, although his interest is not primarily in finding water but in finding support for his occult teachings. He claims (quite mistakenly) that natural science will produce results that lend credence to his “spiritual science.” Actually, the advances that have been made in science since Steiner's time have progressively cut away whatever ground Anthroposophy once stood upon. 

"During our discussions I have often mentioned the natural scientist Moritz Benedikt; his main interests are anthropology and criminology, though his scientific investigations cover a great variety of subjects. 

"...Moritz Benedikt has discovered that when a person holds the divining rod by both prongs the forces in the left side of the body unite with those in the right side. Or, as he expresses it, the forces, by flowing together, form a common stream of emanation. When a person particularly strong in such forces walks over ground beneath which there is water, a change takes place in the forces of both sides of his body. This change is caused by emanations streaming upwards from the water below into the person. It is interesting that Moritz Benedikt, himself a doctor, discovers that particularly susceptible persons can become so strongly influenced that they become ill by simply walking over ground under which there is water or a metal ore. Thus Benedikt found that if certain individuals walked over ground containing particular substances which they either ignored or knew nothing of, they could suffer illnesses such as melancholia, hypochondria or hysteria, illnesses of which doctors no longer know much more than their names. However, when the same individuals held the divining rod, they did not become ill. The rod causes the two streams of forces in the body to unite, and as it dips it diverts the force that would otherwise cause illness in some part of the body. So it is a case of streams of forces being diverted from the body through the rod." — Rudolf Steiner, ASPECTS OF HUMAN EVOLUTION (Anthroposophic Press, 1987), lecture 4, GA 176.

A dowser or diviner.

[Etching by Jean-Frederic Bernard.]

"Natural science is very near at many points to a meeting with spiritual science. I said in other lectures and have indicated the same thing here, that natural science is very near to a discovery of something that has met with opposition even in spiritual science. People who read my THEOSOPHY often find themselves repelled by the chapter where I speak of the human aura and how man's forces of soul and spirit are expressed for clairvoyance in a colour aura that sparkles round him. Now Professor Moritz Benedict, whom I have often mentioned in other connections, has recently made experiments in Vienna with persons who have a gift for using the divining-rod. Professor Benedict did not make clairvoyant experiments; as he is very unwilling to acknowledge clairvoyance, but he made experiments in a dark chamber with those gifted for using the divining-rod, which has played such a great role in this war. You probably know that it has played a very special role in this war. Since water was needed for the soldiers, persons able to use the divining-rod were posted to various army-groups in order to discover springs of water for the men. This went on very largely in the southern areas of the fighting. Driven by necessity, of course, one had to do such things. Now in the camera obscura and with the method of natural science Professor Benedict has examined people who can find water or metals under the earth by means of the divining-rod. In the case of a woman who was quite small, he discovered that she showed under treatment in the camera obscura, an immense aura, so that she looked like a giant. He could even describe the right side as bluish, the left side as yellowish-red. This can all be read today as scientific findings, since Professor Benedict has published the whole matter in his book on the divining-rod. What has been observed by Professor Benedict through these methods is the aura, as I have mentioned on earlier occasions. It is not the aura of which we speak; we mean much more spiritual elements in man than this lowest, almost physical aura which Professor Benedict is able to find by natural means in the camera obscura. Still there is a connection. Precisely that part of my book THEOSOPHY which has met with the most opposition and abuse, has thus shown its point of contact with ordinary science." — Rudolf Steiner, ANCIENT MYTHS (Steiner Book Cenre, 1971), lecture 7, GA 180.

AI would also like to tell you how one can best make use here of previous scientific results. In doing so I do not intend merely to tell you an interesting fact — for outer science is not yet ready for it — but rather to draw your attention to something about which we can acquire quite another complex of thoughts. The Professor Benedikt mentioned above made some very interesting investigations in a dark room on the lowest human auric radiations. These have nothing directly to do with what I have described in my book, THEOSOPHY, for example, though there is an indirect connection. The latter are higher radiations only perceived in the supersensible. But between these higher radiations and the coarser effects seen by the eye on the human being, there is a domain that can be perceived in a dark room. Professor Benedikt has described his work in the dark room in an interesting way. He used individuals who were sensitive to the phenomena of the divining rod, that is, individuals in whose hands the rod moved significantly. Benedikt investigated the auric radiations of these individuals in a dark room. The following results were obtained. The auric radiations of such individuals differed markedly from those of other people in that there was greater asymmetry: the radiations from the left side of the person were different from those from the right. The head radiation was also quite different.

"A beginning has thus already been made in seeing human radiations through physical demonstrations, even though these results are received very skeptically. But we must remain clear that these are only the lowest radiations connected with the human organization. In studying these, one has not yet entered the realm of the supersensible, as many might maintain who would like supersensible investigation to be nice and comfortable. Nevertheless, this is a beginning and could have therapeutic results." — Rudolf Steiner, ANTHROPOSOPHICAL SPIRITUAL SCIENCE AND MEDICAL THERAPY (Mercury Press, 1991), lecture 3, GA 313.

Is it unfair to chide Steiner for believing in divining rods, auras, and other occult nonsense that many people took seriously in his era? By rational standards, it may be unfair. But by Steiner's own standards, it is not. As we have seen in these very passages, Steiner claimed to be clairvoyant. He claimed to have access to information denied to ordinary investigators, information that should have enabled him to avoid the fallacies of his era. But what did his clairvoyance yield? Not  much. It did not even enable him to see through such hocus-pocus as divining rods. Casting about for any shred of scientific information that might conceivably prop up his own doctrines, he fell for baseless pseudoscience.

* Here is how Steiner explained his references to Benedikt. (Steiner had an interesting way of defending himself by denying that he was doing exactly what he was doing. Consider, for example, the contradiction between the two halves of the first sentence; consider, too, the relationship between the second and third sentences.)

"There is no intention here of taking up any kind of attitude toward all that Benedikt has worked out, which belongs to the most interesting modern theories of nature. Neither is it intended to take advantage of a cheap opportunity to make excuses for spiritual science through natural science, which so many enjoy doing. It is only intended to point out how, in one instance, a scientist can be brought to make assertions that are not unlike those of spiritual science. At the same time, it must be emphasized that the aura that is spoken of in this book, and that can only be grasped spiritually, is something quite different from what can be investigated by physical means and about which Benedikt speaks. We surrender ourselves to a gross illusion if we think that the spiritual aura can be one that may be subject to research by the external means of modern science. That aura is only accessible to the spiritual perception reached by the path of knowledge as described in the last chapter of this book. It would also be a mistake to suppose that the truth and reality of what is spiritually perceived can be demonstrated in the same way as can what is perceived through the senses." — Rudolf Steiner, THEOSOPHY (Anthroposophic Press, 1971), addenda, GA 9.

Steiner referred to Benedikt often: 

"Professor Moritz Benedikt, whom I have often mentioned in other connections." — Rudolf Steiner, ANCIENT MYTHS AND THE NEW ISIS MYSTERY (SteinerBooks, 1994), p. 139.

Steiner gingerly endorsed at least some portions of Benedikt’s work: 

"Not without reason have people like Moritz Benedikt warned against a scientific pursuit of the phenomena of hypnotism ... With good reason Benedikt has pointed to the fact that in all the literature of the Nancy School it is not possible to distinguish between what is superficial and what is positive performance ... That is the instinctive judgment of a man — that is, of this very Professor Benedikt — who is, after all, highly esteemed by certain individuals of the present day ... This judgment is significant because it instinctively presents to us the true state of the case." — Rudolf Steiner, SPIRITUALISM, MADAME BLAVATSKY & THEOSOPHY (SteinerBooks, 2002), p. 90.

— Compilation and commentary by Roger Rawlings

[R.R.]