Originally Posted by
VintageR
Yes, should be the signature of the belgian bike 'maker' (really more of a wholesaler) from Herentals/Olen.
Probably produced by SR ~ Sakae Ringyo (model "Apex"?), but on behalf of Norta - not too unusual at that time.
I doubt that it's an "Apex" since I have one also and they don't look alike, but who knows.