RTF templates are identical to PDF templates. The same template can be used to produce output in either format. Again, the template is mostly XSL-FO with XSLT used to insert values from the XML document in the appropriate locations.
The JFOR library is used to render RTF documents from XSL-FO documents, however, not all XSL-FO elements are supported. Unless you need to edit the documents in a word processor after they have been generated, you should use the better supported PDF generator.