Originally Posted by daxmon87
How can I mark the chapters myself so that they will be identified by Calibre?
You don't say how you're creating your RTFs but if you're using MSWord then you should style your headings with one (or more) of the built-in heading styles (Heading 1, Heading 2 etc).
For example if you styled your chapter headings with Word style 'Heading 2' then this is the equivalent of using <h2> HTML tags and you should set [Convert] - [StructureDetection] - [Detect chapters at] to //h:h2
and [Convert] - [Table of Contents] - [Level1 TOC] to //h:h2
Edit: This suggestion is not related to Idolse's pre-processing suggestions