All you need to know about the Bombardier sight, is that once the target enters the centre circle, you hit the Bomb release button.

Normal Procedure for Bombing is to wait for the target brackets to pass under the aircraft nose, and then something like this:

1. Jump to Bombardier seat
2. Select Bombsight, and zoom out
3. Open Bomb Bay Doors (HUD text confirms)
4. Select Weapon 
5. Make minor adjustments to heading with rudder, control stick or differential throttles to keep target on centre line.
6. Zoom in to get magnified view of target.
7. When the target reaches the centre of the centre circle, hit the Bomb release button. Then hit again and again until all Bombs have gone. (Number remaining is confirmed on HUD text)
8. Close Bomb Bay Doors
9. Jump into Pilot seat
10. Get the hell out of there.

or

11. Hit the Bomb view button to ride down with them and see the destruction you have wrought. Hitting the key more than once takes you back from a view of the first salvo to the last.