How can I integrate form calculation into subscription payment options?

https://form.jotform.com/60183995007964 

The first option in this form, "Would you like to cover the cost of the payment processing?  (Adds 3% to your donation)" is what I want for the following form: 

https://form.jotform.com/60146309889970 But because of the limitations on the "Sell Subscriptions" options, ie. unlike the "Collect Donations/Custom Amount Payments", it doesn't have the option to integrate Form Calculations into the Final payment...

So once again, How can I integrate form calculation into subscription payment options?

Hello wamu2323,

Unfortunately it is currently not possible to send calculated amount into subscription payment option. The only option to collect subscription payment is by configuring your payment question option to "Sell Subscription". Please check the screenshot below:

Thank you!