The RCS, like ci, co, rlog, etc. can find in Xcode 5.0(with command line developer tool) in mountain lion, but disappear in mavericks with xcode 5.0.1(with command line developer tool).
Is apple abandoned the simple version control tool?
From Xcode release notes:
The CVS and RCS source control tools have been removed from Xcode 5. 11968433