You should probably try the kile with okular embedded that puts a line in the preview inside the okular part.

I don't see how you would do it with a standalone okular since basically it would mean that a third party thing would change your view, which is not so cool.

I would also appreciate this feature. It's one of the few things preventing okular from beeing the perfect pdf-viewer. But switching to kile is not a real option: Why should you change your bread and butter tool (the editor) if you need a certain viewer feature.

I don't completely understand the 'a third party thing would change your view' comment. If one could toggle the highlighting using a toolbar button/shortcut, it would be the user that changes the view - similar to highlighting of selected text.

The problem that the user might misinterpret the marker/highlight as part of the pdf could imho also be overcome, e.g. be having a simple horizontal line (like kile does) that extends beyond the page margins.

Possible duplicate of: https://bugs.kde.org/show_bug.cgi?id=240315

*** Bug 122599 has been marked as a duplicate of this bug. ***

*** This bug has been marked as a duplicate of bug 377487 ***

I do not think this is a duplicate of bug 122599 or bug 377487. These bugs are about text search while this ticket is about forward search, which is a feature mainly (only?) used when editing LaTeX documents for synchronizing cursor position in the source in the editor and the position in the compiled document in the viewer (i.e., Okular in this case).
Nevertheless, the ticket might be resolved; unfortunately, I cannot test this currently.

Sorry, here I was too fast. Let's reopen it until someone can confirm it's fixed.

Really would like to see this implemented.

For reference, Skim on macOS and zathura on linux both has this feature.