One way to determine what professors might share interests of yours would be to review books and articles you have read on the subject and pay close attention to the cited works. Who writes recent and interesting articles on a topic which excites you? Who has unpublished works in progress which are cited in current literature? If you have a clear conception of your research interests this should not be hard at all. Google scholar can help you here, as you can search by citation and by author (though the author search fails gracelessly when faced w/ abbreviations and authors with the same name). Alternately you can search Web of Science if you have an institutional account or look around for a recent lit review article. When you find a potential match, look for a few things. First make sure they are actually teaching at that school and not on some long term sabbatical or recently moved to some fancier university. Second check their current PhD students to see if they are already supervising a bunch. They don't need to be on your committee in order to mentor you, but it helps. Third (and this relates to the "don't bother"), make sure they are at a good school. Pedigree matters a LOT in academia, don't believe anyone who tells you different. A good dissertation is critical, but an average dissertation from a Harvard PhD gets you a lot further than an above average dissertation from State U. (assuming State U. isn't a public ivy)--that doesn't even begin to touch the non-signaling benefits of going to a good school. Of course "good school" is field dependent. But in most cases the top 10 and even the top 20 are usually the same.
This is all assuming you want to get that PhD in order to teach someplace or do fieldwork. If you just want to learn, disregard all that stuff above about good schools. A lot of those top schools are pretty miserable for grad students if your goal is to learn.
However, if you want to get placed somewhere good, then you can avoid this tedious search and simply apply to the best schools out there and hope you get in a top 10-20 institution. It's really mercenary, but that's how it works.