It's funny that I don't mind handing it out to someone who deserves it (although I usually try to avoid it), but when "for once" I'm suggesting a positive thing here, I'm kind of attacked for it...
Me, I'm not hung up to it -- I'm saying another term would sound friendlier and more appropriate. Tell a Photoshop user to RTFM... The more a product evolves the less it becomes realistic.
To me RTFM suggests to go read the whole manual, although it doesn't literally say that.
Better is, "go read in the manual," "consult the manual," etc.
I think few of us mind RTFM when handing it out. On the receiving end I would prefer to hear something else, as whatever it originally meant, it now does have inflammatory connotations (which may be deserved or not).