WRT has 2 meanings
With regard to
WRT your treatment of Shauna, it's unprofessional and will not be tolerated in the future.
|IRT||In regards to|
|RYC||Regarding your comment|
|FYR||For your reference|
|AYK||As you know|
|ASAIK||As soon as I know|
With respect to
Similar to saying, "In reference to;" might be used to refer to a previous comment or posting made by another user.
WRT what you said earlier, it sounds like updating your system software may solve the problem.
|QRG||Quick reference guide|
|WADR||With all due respect|
|bump||Forum post message bump|
WRT stands for "with regard to." Most often, people use this acronym when referring to a previous topic of discussion. For example, if you've previously asked your boss about a raise, they may open a new discussion on the topic with "WRT a raise ..."
People may also use WRT in a more "out of the blue" fashion, to refer to a person, place, or event that you have yet to talk about. This, however, is more rare. In all cases, you'll see WRT placed in front of the item it regards, to tee up a discussion on the referenced topic.