So we learned how to use CRAFT to give clearances for IFR aircraft. How do you give a clearance to a VFR aircraft? The short answer is that at a Class D airport like HIO you usually don't. You'll learn about more complete VFR clearances at Class B and C airports in the next module at PDX.
If a pilot requests flight following (explained below), it may be up to the radar controller how they want to handle it. You may just tell the pilot the frequency where they can contact approach once they depart. If the radar controller wants you to assign a squawk, you can give a very abbreviated form of the CRAFT:
"Departure frequency 126.0, squawk 1234."
If the VFR pilot is not requesting flight following, there is nothing to give them in a clearance. Just ask them to let you know when they are ready for taxi.
VFR aircraft may request flight following from the appropriate radar facility. This allows them to get information from ATC, especially about nearby traffic. This service is provided on a workload-permitting basis.
A pilot may specifically tell you they want flight following. You may also optionally ask if they do. It can be easier to get that sorted out on the ground than after they depart.
If a pilot wants flight following, you can add "FF" to their flight plan to indicate it. You should also coordinate with the appropriate radar controller to make sure they can provide flight following.
If the pilot does not want flight following, or ATC cannot provide it, then they do not need a departure frequency as part of their clearance unless required per SOP as described above.