Hello Varun,
Not sure if I am late in replying. These SBI don't explain things properly. When you do a sale agreement in Bangalore, as per Karnataka rules you will need to pay 0.1% as stamp duty. 0.1% of the total sale value. This stamp duty can be paid in two days a) e-stamp paper b) franking.
For e-stamp paper you will need to go to sub-registrar office and pay the 0.1% as form of a Demand Draft and buy the stamp paper from them. They will print the stamp paper of the value and give you. There will be space at the bottom of the stamp paper. That is where you need to start printing the agreement content. Rest all pages will be in normal paper.
Franking is little bit easier because you can do it before or after signing the sale agreement. All you need to do it print the agreement and take it to the sub-registrar office. Carry the same DD amount. They will print the value of stamp value on top of the first page.
Check here for a sample franked sale agreement.
https://www.zippserv.com/blog/sale-agreement-format-bangalore/