The Jargon File (version 4.4.7, 29 Dec 2003):

RTFAQ
 /R?T?F?A?Q/, imp.

    [Usenet: primarily written, by analogy with RTFM] Abbrev. for ?Read the
    FAQ!?, an exhortation that the person addressed ought to read the
    newsgroup's FAQ list before posting questions.


The Free On-line Dictionary of Computing (30 December 2018):

RTFAQ

   (Usenet, primarily written, by analogy with RTFM) Read the
   FAQ!

   An exhortation that the person addressed ought to read the
   newsgroup's FAQ list before posting questions.

   [Jargon File]

   (1994-12-08)