chromakey and confusion about alphachannels

Here is a patch to demonstrate my issue..basically i want the ability to apply a blur to the alpha channel of a chromakey so that i can soften it a little bit from its normal chunkiness but i cant seem to order my patches correctly..right now i can just get the a white overlay ontop of the camera image, but i cant get the cutout image on top of the camera with the blurred alpha..im sure its some simple solution but ive been mixing things backwards and forwards for the last hour so i don't think its going to reveal itself