I have seen plenty of recipes for frozen yogurt, but balk at buying
one more machine which I will only use occasionally and have to find
storage space for it. Is the machine really necessary? I guess I
should just mix up the ingreeds and stick in the freezer in a bowl to
see what happens.

I once did borrow an non-electric ice cream maker and the inner
container barely fit in my freezer. I have a side by side fridge now
and I doubt it would fit in the freezer section without a major
rearrangement.

By the way, that Kemp's frozen yogurt is very good. Smooooooth.