Gaurav-
From the Suppliers (or Content) step of the RFP, click the "Excel Import" button. You'll be able to download an Excel copy of your RFP and you can add new suppliers on the Suppliers tab. Upload that worksheet back into the site from the "Excel Import" screen and it'll create the suppliers for you.
If you need any help with the process (as it can sometimes be tricky), let me know.
Also, just a warning: there is a per-event supplier limit. I'm not 100% sure what the current limit is, I think 100, but you may run into errors if you go over that.
Hope that helps!