Originally Posted by
soon2bfo
Since you brought it up,
From
Purdue OWL: Articles: A versus An
"...The choice of article is actually based upon the phonetic (
sound) quality of the first letter in a word, not on the orthographic (
written) representation of the letter."

Thank you soon2b. I knew that saying "an RJ" had to be correct, if for no other reason than "a RJ" sounds onerous and trips up the tongue.
Thanks for the research.