Some were actually sold without RF's, although if the holes are there in the body, it probably had one originally. Extra Kalart rangefinders don't seem particularly scarce on eBay, someone was selling a pair of them on LFF recently. Not all are created equally: I have two Speed Graphics and the RF on one is noticeably brighter and more contrasty than the other.
There are instructions online to calibrate the Kalart, you'll need a tape measure, some small screwdrivers, and some patience to get it done. I found it do-able on my own, although it was fairly frustrating and I'm probably not going to be trying to recalibrate the body for other lenses anytime soon, if ever. Once working though, the Kalart is invaluable if you're trying to take candids/street photographs.