There are safeguards to protect the user if the file is edited outside of RCS, and allows the user to get the RCS archive back up to date.
You can edit multiple programs at a time with something like:
The editor name is drawn from the environment variables $VISUAL, $EDITOR, or (if all else fails) "vi".
Also included is a simple program, show.locks which shows all of the files from the current directory which are currently locked.
If you have files locked, but not currently being edited, you may want to do:
ci -u FILE chmod a-w FILE