The "artist signatures" marks were made by either Eric Dobson or less often, Marie, V. Boffo's neice who worked in the packaging department. They each did make the mark look slightly different, and I have posted images of both here before.
I can't currently post them again because my pc died.
If you dig around this forum a bit you should be able to find them.
It really doesn't matter though. They are just marks that indicate the studio thought they were good enough to have some sort of artist mark on
and that there was time and equipment available for somebody to do it at that particular point in time.
They are not actually real artists' or glassmakers' marks.