Trump has been vilifying immigrants, Mexicans, Moslems, the disabled, and women during his bid for president. This has attracted many racists who now feel they can voice their prejudices openly and loudly. Although supporting Trump does not make one a racist, racists certainly feel comfortable at his rallies. Signs with slogans such as "Make America White Again," "Islamism = Nazism," and "Make America Great Again" (written on a KKK white hood).
Yes, Trump is appealing to racists, because he says things that those people want to hear. He tells them that if he is elected, they won't have to worry about certain minority groups coming into the country. Trump's fan base is largely white and uneducated. He knows this, so he intentionally says things that will appeal to this type of base.
Trump's main platforms include the banning of muslims from entering the country, and the building of an unnecessary and costly wall on the Mexican/Us border to prevent "illegal" immigrants from entering the United States. Need I go further? He blatantly labels minority groups with derogatory and stereotypical terms, painting entire ethnic groups with a condemning brush.
Donald Trump is appealing to racists. His message is one of exclusion, the very definition of racism. He is intentionally targeting angry white males through his rhetoric. He has made racist comments, including those against Hispanics, which he accused of theft. Trump has also made sexist comments, including calling out a woman reporter.
What I find interesting is that in the question the word "appealing" could be either an adjective or a verb, so it can be read a couple different ways. If "appealing" is an adjective the answer has to be yes; while his policies are far from the those of groups like the KKK they're closer than those of Hillary Clinton. If it's a verb then I would say it's an unintentional yes for the aforementioned reason. I don't think Donald Trump is himself a racist, but he does speak brashly and without thinking things through and says some things that may come across that way. If anything he's closer to an idiot than a racist (of course, it's not like those two are mutually exclusive)
Trump's rhetoric skates the line between being racist and not. He's enough of a businessman to not use statements that tie him to a position. He appeals to racist, by inferring and letting people guess his position. He repeats these catchy slogans, like "make America great again" but it always lacks any depth as to what he means and how he's going to accomplish it. Whether the man is racist or not, i dont think many people can answer that. His campaign has been all about bringing in the discontent including racists.
When David Duke endorsed Trump, he said he didn't want Dukes vote, you know who is appealing to racists though, Hillary Clinton, KKK members have endorsed her, and she never criticized them once, she also said that Black youths are super-predators and we should bring them to heal, that's racist.
Donald Trump has provided plenty of ammunition for his opponents by making statements that are offensive to some people. His comments have not been racist, but more about enforcing stricter immigration policy and tightening borders for people from countries known to harbor terrorists. The comments he makes may not be politically correct, but they are not racist.