To set up Razorpay, click the Gear icon -> Integrations -> Online Payments. Click on the Setup Now button under Razorpay and enter the information required and click on Save. As of now, Razorpay is supported only for organizations with India as their country.
Razorpay does not support auto-billing and hence will work only for one time payments.
Books
Simplify accounting
and GST filing.