It depends to me how the anchor asked her followers to vote. If she said something during the news, then that's totally inappropriate in my opinion - not because it's unfair to the other anchor or something, but because it's yet another way that journalists are forgetting what their roles are supposed to be.
However, if she did it in her own time or on her facebook, then I think there's nothing wrong with it. I don't think a day goes by where I don't get an email or see someone on Facebook asking us to "Click this link and vote for my friend please!" - for better or worse, that's how online voting works now. I don't think that practice itself is rude, and I also don't think it's necessary to draw some arbitrary line saying "If you have X number of friends on Facebook, you can ask for votes for friends, but if you have more than X friends, it's wrong."