Originally Posted by ldolse
You could try enabling preprocessing under structure detection in the conversion options - if your chapters are marked with typical chapter headings then it will mark those in such a way that Calibre will build a table of contents later in the conversion process.
"If your chapter are marked with typical chapter headings..."
I don't know if they are marked this way. I make the RFT files myself. I like reading fanfiction, so I just copy stories from the internet.
How can I mark the chapters myself so that they will be identified by Calibre?
Thank you for responding!