rubbing compound is normally used to bring back the shine to paint; either after sanding it smooth, or to remove oxidation, etc. I have never seen it used to de-gloss paint. The issue with sanding it, or wiping on some de-glosser is that it will be very hard to get a uniform sheen. Depending on what you have on there now, your best bet may be to lightly sand it and put a coat of low gloss clear on it (consulting a paint supply store for the proper product to work with what is on there now)
