There is nothing built in that supports this. You'd be creating your own version of a HyperLink complete with the data to identify the place you wanted to go to, a tag of sorts, not a line number.
Line numbers in a RichTextBox are not the visible lines you see on screen. For example, if you have a single line of text with a CR at the end this line can be rendered on screen using any number of lines on screen, though no matter how many lines are on the screen, there is only 1 line of text in the RichTextBox.
There's a couple of articles here on CP that describe something along the lines of what you are. Both have the same title but they are different articles:
Links with Arbitrary Text in a RichTextBox
Links with arbitrary text in a RichTextBox