I'm also fairly new to the class and have been working through how to set up the rig. I'm sure you'll get more expert advice as well.
Generally, the top of a sail should be slightly more open than the foot (due to the apparent wind being at a greater angle to the boat higher up) so set the kicker so the top luff telltale is about 50% flying.
If you rake the mast back, you'll lose a bit of power, which doesn't sound like what you want. You might try raking it slightly more upright (depending on where it is now) or putting on more rig tension, which will bring the mast more laterally upright. The tuning guides on the website will help with this, though my observation is that people are generally sailing with more rig tension than the guides indicate. I have about 180 pounds of tension on the shrouds upwind in a F3, which means the leeward shroud is only slightly loose. I'm going to try with more tension too. (People worry it could damage the boat, but consider how much tension a decent breeze puts on the windward shroud!)
At your weight I would set the spreaders to their maximum length and set the lowers to tighten up as the kicker comes on.
After all that, if it still doesn't work, try putting on some cunningham to flatten the top of the sail. If that fixes it then ok ... but it's also depowering you and probably means it's time for a new sail
Good luck!
Alex
1280