...am writing to you in support"? To me, both are obvious and unnecessary but it's a letter of recommendation that someone else has drafted. I can't come up with a better intro right now though. Help
I would think that : "I am writing to support....." would be more grammatically correct.
If you are having many grammatical questions ask an english teacher or consult some form of an Easy Writer. (if you have no idea what an Easy Writer is, just search for it on google, and yes it is a type of reference book).
