I do not know what "rdate" is. But when I googled "rdate", the responses look like it is used to sync timeclocks. For this functionality I use "ntpdate". It is based on the network time protocol. A machine can sync to another or be configured to be master for other machines. There is also has a daemon program, xntpd, that allows the clock to remain in sync constantly with other machines.
Since the you located the program in an RPM, could it be a RedHat only program. I have run across several program like that.