I bought a RBTA its about 5" when open I was wondering do they split at the foot or at the head? I have had this nem for about 2 weeks and the other day it looked like it was seperating at one side of the head. Anyone have any input?

They split their whole body at the same time, you will probably notice it in the oral disc first though (the head).
The mouth will look elongated (oval shaped) and it will start stretching length wise and not be in their normal rounded shape.

Sometimes they just are in a goofy position or just being goofy in general. If it splits it will do it within a matter of hours its not a long process. Mine usually start and finish in +/- 3 hours.

Mine is doing everything you mentioned except for the amount of time it has been two days since I notice it start to seperate on the disk.

Are you sure its separating and not just being a goofball as they tend to do? It could just be stretched out and have a crease across its disc.They literally tear themselves apart, so you would see strings of flesh between the tear and their white-ish clumpy insides. A picture would help. Heres a picture of my rose splitting:

Nah it must not be it was clean when I seen it. Bummer I got really excited too.

In all honesty you will be lucky if you catch them splitting, usually you come home and boom theres more than one. I woke up in the middle of the night and checked the tank as usual and there it was ripping apart. Last split before this one i came home from work and there was two (GBTA not my rose).

It took mine about 4 hrs from start to finish. This happened 2 days ago. I waited for weeks in a row to happen and nothing, I was thinking of doing the manual propagation with a razor blade but couldn't get it out if the crevice where it was parapeted. So after some deep thought I decided to place the whole rock upside down with the mouth facing the sand and left it there for about 6 hrs. Next morning it started to split now I got two.

You stressed it into splitting. Not a bad way to do it IMO, some people do some terrible things to get them to split (when its easier, quicker, and safer just to cut them). I've heard of people doing massive water changes, doing odd feedings, screwing with temperature swings and messing with water quality.

You lucked out on that one, and waiting weeks isnt that bad. I waited 5 months and had a 10inch anemone when it finally split.