Is there any way we could process the purchase receipt so that it indicates the bill was paid with a credit card?

Yes, you can do that. 
  1. Convert the purchase receipt to a bill
  2. Click on the “Pay Bills” button from the “Vendors & Purchasing” tab of the Start Menu, the screen with all of the vendor bills displays.
  3. Check the box to the left of the vendor bill you wish to pay.
  4. In the top section locate the drop-down to the right of “Payment Method”
  5. Choose a credit card for the payment type from the drop-down.
  6. Click on the “Post” button.
The bill will be marked as paid and is included in the vendor’s history.