I made up a one page form that I gave to each place to keep track of my hours. Some of the schools I applied to had specific requirements about what would count and some didn't, but I just submitted the same form to everyone. The form basically listed:
-facility name and location
-dates and total hours of observation
- checkboxes for type of facility (school, hospital inpatient, etc)
-a comment space for the OT to write a few sentences about the work I observed
-a space for the OT to fill out contact information and sign off
This may have been overkill, but I shadowed several OTs in different kinds of facilities, and I wanted documentation that easily reflected that. As an added bonus, some of the OTs used the comment section to write nice things, which in a way acted like extra recommendations! Obviously there's no way to know how much that helped me, but it didn't hurt.