RTFM was used in the US military, and was apparently familiar to many of the troops by the time I had any contacts there, but my direct experience with the military doesn't go back quite to the Korean era. It was a well established usage very soon after that, however, and must have been well known before then. In the military usage it had nothing to do with computers, and "Army Manuals" were a fact of life at least back to early WWII days (and some of them are still pretty good).

On the computer side, I don't immediately find a historical lineage for any of the "RTF" series of "replies to ..." but do note that the New Hacker's Dictionary 2d edition (1993) refers to RTFB as the only one not used as at least mildly derisive/derogatory to the one to whom a reply is directed.

Since hardly anyone before the Korean era would be likely to know how to Read the F*g Binary (even if such a thing had existed) the whole set as used by computer geeks probably isn't older than that. (RTFB was mostly used as an expression of exasperation over the complete non-existence of any documentation or other information about something that doesn't work, as in "Oh SH*T, we're gonna hafta RTFB.")

An intermediate term, RTFS (Read the F**g Source) would be preferred if the source code was available, and could be used as a "reply to" or as a simple "resigned declaration," so of course RTFB was appropriate only if even that didn't exist.

In UK usage, it's reported that a first response to a "newbie" question might be just RTBM (Read the Bloody Manual), followed by RTFM (considered "stronger language") if the newby came back for more.

The "more polite" RTM also was used, although infrequently in my experience.

RTFAQ also appeared pretty far back, but presumedly only after the FAQ form/method for evading support questions was fairly common. Since at least those who got paid for something did - until recently - provide at least some support for their products, that particular one is likely to be one of the "youngest."

There have been prior threads here discussing origins of some other terms (SNAFU/FUBAR, et. al), some of which do have known usages going back quite far; but I don't recall the RTF* series being included.

John