Accompanist fees are set in the Exam Codes file, by selecting the red Accomp Fees button.
Add a new record using the green + button. Select a grade and enter a cost. You can make a note, e.g. to indicate how many and what length rehearsal/s a student should be booked into for that grade.
Note that you need to set up an accompanist code for each grade, in order to bill for accompaniment for that grade.
See also Send Accompanist Fees to Accounts File.