Oil leak?

[Dead Eye]

There is no oil behind the cover you have highlighted (at least not as far as I'm aware) so if it's that far forward I'd suggest looking at the oil cooler / filter on the front of the engine. Mine had quite a fast leak and the entire side and underneath of the bike was covered in oil.

The other option is to replace the gasket on the clutch cover which is the cover next to the on you've highlighted towards the rear of the bike