Get the source distribution of RCS Version 5.7. It is available at
and its mirrors. After you have unpacked the archive into your source tree, you need to configure RCS for your system. This is done via the
configure script in the source directory, which you need to execute first. This will generate a
Makefile and the appropriate
conf.sh for your system. You can then type
which will build the binaries. At some point you may need to
su to root so the binaries can be installed in the correct directories.