Firsr of all, are you sure it's "silicon" caulk you need, and not a simple latex based caulk. You do not want to use silicon unless that was what originally there. Once silicon caulk is used, it's a pain to remove, and nothing will stick to it. If you dig a bit you will find posts about owners trying to remove old silicon and what a pain in the arse it is to remove.
You never want to use a silicon based caulk on the exterior, for the same reason, plus it really dosen't seal that well. For anything on the exterior use Dicor Lap Sealant which is a regular caulk for verticle surfaces, and Dicor Self Leveling Sealant for flat surfaces like roof vents.
If what is there originally is silicone, than that's a different story--use similar to replace it. As for the interior, many latex base caulks come in colors. Just check your local Lowes, Home Depot, or even Amazon. And, the stuff is cheap. A tube of almond colored bathroom caulk runs about $4-$5 bucks. and was enough to completly seal my shower.
I won't let a tube of silicon caulk come within 50 feet of my rv.