Adding a processing fee

Navigate to Settings / Billing / Payment Accounts.

Locate the payment account to which you want to add a processing fee. Click the three dots button next to it, then select "Edit".

Within the payment account settings, find and click the "Add Processing Fee" button.

Here, you have the option to set a flat value, a percentage value, or both for the processing fee.

Once you've configured the processing fee to your preference, click "Confirm" to save your changes.

If you have other payment methods that also require a processing fee, repeat the same process for each of them.