HDV cannot be exported as a QT Ref file. You have to transcode to DNxHD first, then export that as QT ref.

Select your HDV sequence. Duplicate it. Put it into a new bin to keep things organized. Now select the new sequence and transcode it to DNxHD. The bin will fill with new DNxHD clips, which , if everything goes according to plan, will be linked to the new sequence.

Once you get this far, if something still is not working, now is the time to post a question.