Okina & the Islands

I was just wondering which of the islands (besides O‘ahu) take an okina. I've flipped through some of the locally produced magazines here and I can pretty much guarantee that I'm not the only one with this question. I saw the okina popping up in what seemed to be really awkward places (Mau‘i). But I can't deny that finding an answer is hard - I've tried looking up the correct spelling on the state's website, wikipedia, random google searches, etc., but so far the results have been so inconsistent! This leads me to a secondary question as well: what kind of resources would you consult in order to check the on the definitive spelling of Hawaiian words?