I see much unclearness on how it applies, esp. since PCs DON'T usually stay in 1 area.
I've seen comments from Paizoans suggesting it applies to ALL "Localities"
...That doesn't make much sense, but if that is the "canon", it should be clarified as such.
Instead, though,
Why not link it to Regional Affinity, and say it applies to ALL areas you have an Affinity with,
just to not give a completely narrow (1 location) use...? (this also re-inforces the Regional Affinity concept)
Like Languages, PCs could start w/ 1 free Affinity, & bonus ones = to CHA bonus.
More Affinities are only gained in the manner described in the Campaign Setting.
(you need to spend a year, spend 1 rank in Know(Local), etc, to gain a new affinity)
Maybe your Affinities are always limited to your CHA bonus (minimum 1), so unless your CHA increases, you need to drop a previous Affinity to gain one. (you'd still have any Regional Feats, etc from the old one, Know(Local) just wouldn't apply any more, and you couldn't pick up NEW Feats from that Region) This would just represent that a person can only "stay in touch/tune" with so many different locales, while making high CHA characters most adept...
...thoughts???