Paul,
I too used to think that KS stood for Kearny Specification. But there is a lot of disagreement about the meaning. People like me thought it had something to do with Kearny Works (Kearny Specification, etc.), but KS-specs actually preceded Kearny Works!
There were KS-specs for EVERYTHING! Our company would figure out the best way to do everything (by having experts and Time and Motion Engineers study everything) and they'd document it so all (mostly internal and suppliers) could follow the specifications and procedures and would know how to do it right. I remember once my dad even showed me a KS-spec for how to mow the grass at Western Electric locations! Some people thought our specifications were too rigid, but that's how we were able to ensure quality and reliability throughout all our products.
Heck, the 5ESS landline telephone switch achieved an average of 99.9999% uptime (as filed with the FCC). That means if you added up all the uptime and all the unplanned outages, the average downtime you could expect from your landline would be less than 32 seconds a year. It was not uncommon for a telephone switch to not have any unplanned downtime for 20 or 30 years or ever. Compare that to Comcast's boasting of 99% uptime for their VoIP "landline" service which means on the average, your landline would be out of service more than 3.5 DAYS a year!
I've never heard nor seen any RS- specifications.
I come from the Western Electric, AT&T, Bell Labs, Lucent, Alcatel-Lucent and currently Nokia side. I didn't have dealings with Teletype in my professional work life... just now with my hobby interest in Teletypes (33's and 43's). So if RS- specs were part of Teletype, sorry, but I wouldn't know.
Chuck
W9CFR