any reason you prefer this archiver? and version?
I prefer 7zip myself. since it is available in source file and can be compiled for just about any OS I run. Plus it handles zip, tarballs, rars as well as its own native 7z format.
maybe you can contact the author of RKC and see if they have an older version they can email you or point you to a link.
maybe someone on the board will have an old copy.