How do I apply the Check Point RMS to the densified image measurements after accepting the final adjustment?
You must first have check points to start this procedure. It is best if they are separate project planned check points at varying elevations evenly spread across the project area. If these were not planned (feel shame), then it would be better than not having check points to change the type of some of your control network to temporary check point type to accomplish a computation of the RMS. Again, this should be well distributed over the project area as a good sampling (do not forget to return temporary check points to control points for your final adjustment before the next densify step).
Run the Photo Triangulation Adjustment in the Absolute mode. In the Summary Stats tab please find the RMS Check stats and write down the values for the XYZ. I use the highest of these values to then apply to the standard deviation setting on the Photo Triangulation > Densify…>User-Defined Standard Deviations.