I ended up reinstalling rvm.
There is a function to add managers, however it requires that Mult-User is enabled from a super user installation.
From the RVM guided installation:
After following above instructions for Multi-User.
For each user that want to use RVM, an additional command needs to be run (once) for each user:
rvm user gemsets
but the Multi-User
function should have been enabled first:
The (Multi-User) rvm function will be automatically configured for every user on the system if you install with sudo.