The router bit that I am looking for, as noted in my post, needs to be a 1/4" shank but the bearing needs to be on the "other" side of the carbide cutter. I have numerous rabbeting bits but the bearing is on the 'wrong" side of the cutter. I need one that has the bearing on the router side of the cutter. I hope this makes sense.
Yes, that is a top mounted bit. Am I correct in assuming the doors are already assembled as in the picture? If it isn't assembled already a rabbeting bit isn't necessarily what you want, and I don't think I've ever seen a rabbeting bit with a bottom mounted bearing. If it isn't assembled, you can simply use a straight bit and run the piece against the fence and you don't need the bearing, depending on the profie of the piece. For either a bearing or a fence to cut a rabbet, the profile must be flat to a height slightly higher than the rabbet so there is something for the bearing to run against.
That's why I mentioned attaching a straight edge for a mortising bit's top mounted bearing to index against.
Is the door already assembled or still in parts? I suggest you take a bit of scrap material you used for the rails and stiles, and on the end, mark out what you want to cut out. If there is straght material left above the rabbit, then you have a lot of options. But I still would not use a rabbeting bit if it's assembled already.