For a Copyright fee that requires GST to be included on the invoice: 

1. Create a new category for Copyright/Royalty. [Admin] > [Accounts and Category Setup].
2. Create an Invoice or Receipt to register the money coming in. [Sales/Receipt] > [Add Invoice] or [Add Receipt]
3. Add a CREDIT to the artist's account. [Accounts] > [Artists Payments].
4. Add a payment to the artist's account.

For a Copyright fee that can be paid direct to the artist (such as from Copyright Agency/Viscopy) and is GST Free: