Parade Rest Procedures
Place the butt of the rifle on the marching surface, centered on the right foot, with sights to the rear.
The toe of the butt touches the foot so that the rear sight and pistol grip form a straight line to the front.
Secure the rifle with the right hand in a “U” formed by the fingers (extended and joined) and thumb.
Slide your hand to hold the rifle above the front sight assembly with the right thumb and forefinger pointed downward, and on line with the flat surface of the handguard. Keep the right hand and arm behind the rifle so that the thumb is straight along the seam of the trouser leg.
Video:
http://www.pdf-archive.com/2014/01/22/army-tc-3-21-5/army-tc-3-21-5.pdf
Page: 5-2 and 5-3