The RC-3 Kydex sheath is the same as the RAT-3 sheath. You can arrange it and the TekLok to go horizontal and put it in the small of your back. If you don;t like it, I would say look up Fellow Forumite Normark, who operates a tactical sheath making business (just can;t remember the name right now...somebody'll be along shortly to provide it). He's probably the most revered Kydex sheathmaker in this Forum.
I have a big problem with the RAT and RC Kydex sheaths paired with the TekLok. A complete blunder of a marriage. Neither designed their layout holes to coincide with the other, so matching up more than two configurations of attachment is painful to the point of being sickening. Piss poor would be a compliment. Contact Normark for a real rig and the RC-3 will sit back there pretty nice.