I am building a tile shower in our master bathroom. The framing is done. I am trying to plumb in the p-trap under the Oatey drain I received with the Goof-proof shower kit (pre-pitch sticks, etc). I notice there is no way to bolt this drain to the new 3/4" plywood subfloor. They also do not tell you whether the drain sits flat on the subfloor or whether it sits on the four protruding "knobs" which house the clamp down bolt threads. By the look of the slim end on the pre-pitch kit, it can sit directly on the subfloor with the knobs through the plumbing hole. I am asking if that drain just sits there until the mortar bed or tile bed holds it in, or if you're supposed to caulk it to the subfloor. I would also like to know does the drain sit directly on the subfloor, or on those four knobs? I know the p-trap directly under the drain must be perfectly level for drain to sit correctly. I am pulling my hair out! Help!!