What percentage of the US dollar index basket is the the CHF worth?

A mere 3.6%.

Devalue that portion by 10% and those short the DXY are suddenly in a world of hurt.

The combination of the weak euro and the devalued franc has pushed the DXY up 0.66% today.

Next resistance for the index is at 76.26. If that breaks, the mid-July lows at 76.72 comes into play.