Acronym for Scientology's Rehabilitation Project Force (q.v.). Hana Eltringham Wakefield, a former executive (Deputy Commodore of the Sea Org -- i.e. Hubbard's deputy) in the Church, and someone who was exposed to the RPF in 1978 -- four years after its creation -- describes it thus:
RPF members ... were completely segregated from "normal" staff and slept, lived and often ate in the Fort Harrison(*) garage in the midst of continual exhaust fumes. They were not allowed to talk to, mix with or eat with "normal" staff. They wore old, tattered, ripped up navy jump suits or boiler suits and looked just like derelicts from skid row. Women were not allowed to us any makeup or have any hairdos. No jewelry was allowed. Even in the incredible hot and humid Florida summers, women were not allowed to wear short cut-offs but had to wear longer shorts or skirts or long trousers. ...

-- Affidavit of Hana Eltringham Whitfield,
August 87, 1989

(*) The Fort Harrison Hotel building, in Clearwater, Florida -- part of the Flag Land Base ("Flag").

She goes on to explain how they had to run everywhere, all the time, never being allowed to walk, and how they could not ever use the elevator instead having to run up and down 12 flights of stairs. They slept on the floor, and when performing their ablutions were not allowed to shower for more than 30 seconds. There were no holidays, no days off, and even worse still, the RPF had its own RPF: the RPF's RPF:

... A place in the lower boiler room under the Fort Harrison Hotel, among the boilers and hot water pipes which rumbled and hissed twenty-four hours a day. The place was only dimly lit. It consisted of interconnecting-spaces through which one had to crawl on hands and knees at time past or underneath huge pipes and massive 10 foot high boilers. It was a dark, forbidding, somewhat scary place.
Scientology maintains the RPF was established for the stated purpose of "rehabilitation and redemption". Survivors maintain it was established for torture.