Here is an authentic Knopfler (and John Ilsley) obtained in person when they were here in Finland.
I've never seen anything close to a legible Knopfler autograph. Always heard it was some form of symbols or hieroglyphics. I got one many years back at a long gone venue but don't recall what that one looked like and probably sold it back then. The only time I have gotten him or tried since was Sept 2016 arriving to the venue, I was the only one as others had left. And this is the autograph he gave at the Dallas Majestic. Very similar to the magazine within this thread, and the orig sig in question a little similar as well.
Based on Juha's attached autograph, it looks like Mark signs "M Kpfr" in single markings on mine and others.