That looks like the smaller of the two models (same as the Iver Johnson version). It was about the size of a .25ACP handgun.
I once had an RX-22. It was the same size as a Walther PPK (NOT the PPKS), thus a little larger than the one shown. I got it as an understudy for my PPK in 32ACP. That was before I started reloading .32ACP and the .22LR was much cheaper.
The slide was a zinc casting. After only about 1,000 rounds or so, the ejector (not the extractor) became hammered over and it refused to eject. No way to repair it. I sold the reusable parts on eBay for about what I paid for it.
Thanks for the report. Very interesting.