We can’t link to paragraphs but there are options options in the link syntax
See the Devonthink documentation: Item Links
I don’t use RTF documents, but here’s a link to text generated by the Edit>Copy with Source Link
for the word Testing on page 3 of a pdf
x-devonthink-item://0E29D9C2-39FF-468D-B46C-9F0F91FA128E?page=3&start=863&length=7&search=Testing
Using the link, shows me the exact location in a pdf, with the search text highlighted