RTFFAQ! (How does that sound to you?)
Remember, there are plenty of forums where people can go and receive a snarky "RTFM". Those sites aren't helpful. The SE community exists because we believe it's possible to answer questions in an informative and friendly way.
Your answer would have been received better if you said "Read the manual", or "It's in the manual" instead of "RTFM!". Do you use the phrase "f*cking manual" in real life? Probably not, because people would be offended. It's not that much different here. In fact, your comments are more likely to be misinterpreted because it's hard to communicate emotion using written text.
The comment "RTFM" would be perceived as snarky by most people, and the explanation point adds to the snarkyness factor.
However, when I read your comment in context, it doesn't really seem all that snarky to me.