Just an update ... after struggling with the Silesian foot I did contact the company. Long story short, they agreed to refund the cost of the foot and rulers, although I did have to post them back to Poland. I will say that they couldn't have been more helpful.
I would still buy their rulers, as the markings appear to be a perfect 1/4", they have a great selection and they would work with the Westerlee foot that I have now. I'll check them out when I go to the Festival of Quilts in Birmingham next year.