I think you should be able to do that (using the credit card option). The payment options might be different depending on what region you are in. If it doesn't work directly perhaps you can link your card to a paypal address and complete the purchase that way.
As a developer I don't have control over the payment system and don't know the details of how it works to be honest. If you need more detailed information I suggest you contact the staff at Itch directly, they handle all the payments.
