7. Subtract the Recoil Compensation from the number of rounds fired this Phase, then subtract one; the difference is the recoil modifier.
8. If the weapon is a heavy weapon, double the recoil modifier.
9. If the weapon is a shotgun and the fire mode is BF or FA, double the recoil modifier.
10. If the recoil modifier is greater than zero, subtract it from your pool.
Its really simple. A gun in Burst Fire mode shoots 3 rounds in each burst. You can do two bursts as a complex action. Now, this kicks the gun a bit, making it move off target. Each bullet after the first subtracts from your dice pool, so you'd be getting a -5 to hit. However, there are things like gas vent systems, personalized grips, shock pads, and the like that help you negate some of that kick. So if you have a RC on that weapon of 4, then that means you only get a -1 to hit.
Now, some guns kick more than others. Heavy Weapons (machine guns, grenade launchers, assault cannons, etc.) and shotguns in Burst Fire or Full Auto mode are the main candidates. Because these weapons kick more, any recoil you don't compensate for with RC counts double. So in the example above, you'd take a -2 to hit, while if you didn't have any RC at all, you'd take a -10 to hit.
It may look like a lot, but it is really simple once you get the hang of it.