That is the issue with ClearCase: it is a file-centric CVCS (Centralized VCS), as opposed to git (revision-centric DVCS or Distributed VCS).
See "What are the basic ClearCase concepts every developer should know?" for more on the differences between the two.
If you have a full ClearCase installation in addition of your RAD, then you can directly checkin all checked out files, like in "Recursive checkin using Clearcase".
But if you are using CCRC, it is not so easy to chain multiple checkins, beside the "multiple selection" that you are using.
As the OP nerdherd mentions, CCRC GUI has a find checkout option (mentioned in this technote), which will allow to list and check those in through an (again) multiple selection.