Free Return Shipping Question - Credit Card as Funding Source

[DavidLopan]

Hi - I just had a quick question regarding PayPal's free return shipping option.  I'm sure this is covered somewhere but 

I was unable to confirm if the free return service can be used when a credit card stored within my PayPal account has been 

used as the funding source - or is it only when one's basic PayPal account balance is used?  Thanks much in advance for any response.