Storing directories in RCS

I am having a problem with rcsclean ending with an exit code of 1 when
my RCS directory contains another directory.  Here is my directory layout:
  .svn
  textfile
  RCS/.svn
  RCS/textfile,v

If I issue an 'rcsclean' command, it reports 'RCS/.svn is not a regular file.'

I know that I SHOULD NOT be storing a directory within the RCS directory.
However, it isn't my choice.  The RCS repository is vendor code that I
must maintain in an RCS format.  And I would prefer to store the RCS
repository with other files in a Subversion repository.

Are directories within the RCS directory permitted?  If not, would there be any
problem if rcsclean just skipped over directories like it already does with
. and ..?  I've patched my own rcsclean to skip a directory having the
name ".svn."  But if it isn't permitted to have directories in the RCS
area, I can work on a patch to just ignore all directories.

Thanks,
Paul