ignoring Dr. Bill's standard anti-YART screed, and as perpetrator of the offending term, I stand on shaky ground and state that you shouldn't add an article if you tend to expand it upon seeing it; but rather if you tend to see it as a word unto itself; i.e., yart; then it takes an article just as does any other acronymic noun (not able to think of another example containing an article at the moment, but you see what I mean).