Flouride is much harder to get rid of than most other things.

You really do need to test the water first to know what you're dealing with. Not having a clue can lead to less than satisfactory results.

In your case, you might need to add an RO section to get the results you want, but, in order to make an RO filtration setup work, there's a bunch of prefiltering that should be done in order to ensure that the RO membrane will last.

You'll also need to decide how much filtration you want for the whole house vs. point source filtering for drinking/cooking. While house RO can get silly expensive.

The other thing with filtration is that you can take out so much that you really should re-mineralize the water used for drinking/cooking.