Ok, in this scene I was using an omni light at 50% above the scene which was casting the shadow and using the skylight at 50% to fill there rest of the scene.
Used a target spot (shadows off) you have to come in from an angle and bounce it through the rim and enable secondary illumination / caustics and set the bounces to at least 3.
This will fill the rim with a healthy gob of light and then you'll need to use video post to glow (apply an effect ID to the rim).