@Dzik Hah, I bet he read it as an F; “Oče naf, ki fi v nebefih”. And yeah the ſh looks like an weird m now that I look at it. Interestingly though some people with a lisp pronounce their s as an f. I wonder if this has any connection to why the ſ and f look so similar.
And yes, kust is a dialectal form of the standard kost. I took it from a rhime from my family’s place of origin. It is to honour the glorious Zasavska region, proud home of the expression “mat ku*ba” similar to the Polish “ku*wa mać”