Thanks for joining this thread, @Rjhouseman93.

As my colleagues mentioned above, billing your client for a processing fee is unavailable in QuickBooks. This is because other states prohibit the issuance of processing fees to clients.

As an alternative, you can manually apply the charge to the transaction. For detailed steps, you can follow the steps outlined in the answer of @katherinejoyceO. But before doing so, make sure to inform your customers about the charge before you invoice them. 

Additionally, I've attached a link to help receive and record invoice payments in QuickBooks Online. It includes steps to enter payment for single invoice and partial payment. 

Keep me posted if you have further questions in managing processing fee in QuickBooks. I'm always around to help. Have a pleasant day!