Yes, it's correct to use an income account for the processing fee, Eve2019.

You can create a service item and add the processing fee to your invoice.

Here's how: 

1. Go to Sales, then choose Products and Services.
2. Click on New then select Service.
3. Enter the name of your service item. 
4. Select the account you'd use to track the processing fee under the Income account drop-down.
5. Click Save and Close.

You can also record credit card charges directly from the Merchant Service Center. Please check out this article if you want to know more about the process: Process payments in the Merchant Service Center.   

For future reference, you'll want to categorize bank transactions in QuickBooks.: Categorize And Match Online Bank Transactions In QuickBooks Online.

Let me know if you need help. I'll be here to assist you.