save skim annotated pdf as pdf with annotations

I have skim version 1.4.16, and I can't find a way to save a pdf with skim notes as a pdf with annotations that preview 8.0 can read. I can export as a "pdf bundle", but preview 8.0 doesn't want to open such a file. I expect there are many other pdf readers, both in osX land and other OS's, that won't understand the bundle. Have I missed something?