Some people suggest sprinkling the seed on top - thats it.
Others say sprinkle on top and press into the top with your fingers so they are level with surface.
Some say bury in the soil a distance of twice the diameter of the seed.
I've tried all three and they all seem to work with the right heat and moisture / humidity.
Mostly I just sprinkle them on the surface - but if its an important seed, for the sake of variability / success, I always do all three in each pot - just in case and then I don't have to be too critical about temps and moisture - some will always grow.