Hi Mike,
When you installed SRM, did you select the option to install vSphere Replication in the SRM installer? Even if standalone VR is already installed, you still need to select this option when installing SRM. See step 4 in Install the SRM Server.
If you installed SRM without selecting this option, you do not need to redo the SRM installation. Just run the SRM installer again in Repair mode, and select the Install vSphere Replication option. See Repair the Installation of an SRM Server.
Hope this helps, but if this does not resolve the problem, please let me know.
Thanks!
Stuart
SRM docs