On last week's Gardeners' World, Monty Don dug in his green manure, so I did the same today. As recommended on the seed packet, I cut the green manure and left it on the surface for a couple of hours before digging it in (Monty didn't do that). I then dug it in with a spade, trying to turn each clod upside down before dropping it back.
It was quite difficult to get it completely dug in, so I left a bit sticking out.