Originally Posted by Chain
Rotating/transforming him a bit does help. Getting the perspective to look believable is important, however it can be tricky.
The second shot of the boy might already have a shadow in the original image that you can re-use? I imagine they were originally shot on the same background so it shouldn't be too hard to blend together...
Also, it seems the two images have a different exposure, at least the upper body has quite different brightness. I'd at least try to see if tweaking that helps a bit.
Those are great points- thank you. I will go back and look at that and see if had changed my exposure... may very well be the case.