Skopje is not an English word. In basewords of English origin, the letter k would not precede the o; this would be the job of the letter c (k before e, i, and y; c before a, o, u, and all...
The Skoda dealer in my town pronounces it with a hard K, as do the UK adverts. It might well have a different pronunciation in the original Czech - more Schkoda - but someone would have to be really...