As above really, open up the fold slightly, 'clip' one side in and they you should be able to persuade the other one over. Pop your windscreen in before welding it fully though, just to double check.
Last one I did (72) was the repro igp panel - it's the only panel available in the uk - and it went on fine, the one before that (7
was a bit tight on the edges so I gess it's individual to each avn tbh