You need to seal around the half moon seal, the workshop manual says to only use silicone around the half moon seal and the end cam caps....
But when i asked some more experienced members who have done it heaps more than me and they said to use it all the way around. But don't put it in the groves in the rocker cover, or you'll make a mess for next time, only apply to the head surface.
Clean up the head surface real good with some razor blades first.
With how much silicone to use, don't go crazy or it'll just spit out the sides anyway, but put enough so its not see through, if you get me.
And push dollops inot the corners, and in the corners of where it goes over the cam caps.
And +1 on re torquing them after a few hundred kms.
And torque it up gradually in a criss-cross pattern as it will keep settling as you do it.
A lot of silicone's now say you don't need to do a re torque later, but i did it finger tight, then let it dry over night and the next day tightened it a tad more.