Urgent: amount of stamp paper for licensing agreement

Dear Members

Kindly let me know how to determine the amount of stamp paper for Licensing agreements (for IPR, Patents, technology knowhow).

Specifically i wish to know what should be the amount of stamp paper for an amndment to a licensing agreement which was done on 50 Rs stamp paper.

Kindly reply as early as possible as I have to take the desision today

Thanks