These legs on the side slide in really snugly to the grooves. Other than that it is just resting there. The ray 2 comes with a removable foot for the inside of the rim + plastic screws on the outside (you can see the screw holes on the side of the feet), but they DON'T fit over the rim of my tank. My tank's rim is 5/8 and they come up just barely short.
Between the middle brace and sticks coming out of the water I think this setup is fine, also it allows me to slide the light forward/backwards really easily during maintenance. You've inspired me to go ask in the Finnex subforum if they have bigger mounts though =p. Shouldn't interfere with a glass top.