From what I've read and heard regular water softeners will deplete the RO cartridge faster, then I also read one time that if water is hard to run through softener first. This probably won't be the case with the kinetico system though because I believe they don't use salt in their systems.

Call one of the local water softener companies to check on how they should be hooked up and what you can expect, most of them work in RO units as well as softeners.