VPN Setup - Gateway and Static IP Question

Purchased two Cisco VPN routers (RV130W for small business) for a main office and new off-site bulding.  Both routers are functional doing routing, dhcp, and WiFi.

Now for the VPN between the two sites - the off-site building has one computer that needs connection back to the server.  From Comcast a Gateway and Static IP was purchased.  However, the Cisco is asking for the 'public IP'.  I guess I use the gateway IP from Comcast?  Correct?

Thanks.