Paypal button

I’m new in this forum not sure who to ask but i need some help please
I would like to know if buying your paypal add using nexform would I be able to create an a form like the one below In the link below ?
if you see the form the most importatn field is transaction fee were the clienmt type the amount and give you the transaction fee amount
thanks

Link
https://www.imrtransportation.com/payments/