Refund fee for activity

We recently had our ward Super Activity. One of our members paid but wasn't able to go. Each time someone has paid for the activity, I put it into the Other category (we have an "Other: Super Activity" subcategory). I've heard that I need a receipt in order to write any checks like this, so I'm wondering, what I should do to refund this person's money? Thanks.

EDIT: (From asking a former clerk) It sounds like I can just attach a photocopy of his donation slip or write "see donation slip from [date]" and just write the check.

The bishop needs to approve all disbursements. Most units use a reimbursement request / disbursement form for that purpose. I suspect that is what is meant by needing a receipt. Once the form is filled out (the purpose for the disbursement would be a refund for the activity) and the bishop signs it you can write the refund check to the individual.