The reason documentation is sparse specifically for the 1200R in this instance is that, when the 1200R is centrally managed, it's treated like any other Check Point gateway running R77.20 (with some limitations).
The one limitation relevant to this specific use case is that the Mobile Access Web Portal is not available on the 1200R (or any of the SMB appliances for that matter).
The general VPN documentation for R77.x, which covers Remote Access, is here: https://sc1.checkpoint.com/documents/R77/CP_R77_VPN_AdminGuide/html_frameset.htm
For each 1200R you will need to have an encryption domain defined.
Each 1200R you want to access resources behind should have unique IP space behind it (not used behind other gateways).
Each 1200R would be added to the Remote Access VPN community.
Hope that's enough to get you started.