Shadow only plane 2.72

I cannot seem to find how to only render the shadows from a plane but not the plane itself (hope that makes sense).
basically i would like to render a object along with its shadow, but not the surface the shadow is on.

i would appreciate any help,

Thanks

For some reason you don’t mention the renderer you are using so I’ll have to assume you are using the blender default renderer. In the planes material settings enable the ‘Shadows Only’ option in its Material / Shadows panel

Sorry, no i am actually using cycles. Is this something that needs to be done in composting rather than in the render itself? I cannot find any settings to show shadow only in cycles