I'm using TextEdit on the Mac to create the RTF files. I don't see any options for Headings though.
I also have Pages and I know you can use Heading styles. They aren't labeled as Heading 1 or 2. Just Heading, Title, and Subtitle. I'm thinking that Heading would be the H2. (Title being H1 and Sub-heading being H3).
I'm going to experiment with it a little and see what happens.