This process is often used when you have a vendor account that is also a customer. If the vendor issues a credit to issue against an invoice on the AR side, you can apply the credit within the AP process to apply it against an AR invoice.
This will be completed in the AP Invoice entry section of Softbase. You will add a journal, then enter in the vendor and the AP invoice # and the credit amount (if it is a credit invoice it will be a negative amount). It should default to the correct payables account in the drop down based on the vendor record but you can check this as well. You can adjust any of the dates as needed, and then click the add button.
Example below:
For the distribution, you will simply update the account # to be that of the Accounts Receivable GL that the sales document posted to, and then enter the customer number, Invoice number, and the amount to be applied (this will also be a negative value to decrease the AR). When that is confirmed, click to add the distribution.
When this is completed, you can continue to add lines as needed to equal the total credit to balance the entry and post to the GL.
Once you post, you will see the credit applied as a voucher in the AR inquiry window.