How dumb.  I've been trying for 30 minutes to figure out how to get a blank line (an empty line) between two of my TITLES in my ODS RTF output.  All you have to do is skip over a TITLE statement!

In this example, just avoid using title2 to get an empty line between title1 and title3:

title1 'This is my main header';
title3 'This is my sub header';

And your output will be:

This is my main header
<empty line>
This is my sub header

The SAS Docs have a nice section on Titles, Footnotes, and Notes.