Having a bite or two of milk chocolate or dark chocolate Kit Kat will not harm your dog.
It is because they are chocolate-covered biscuit wafers.
The four-finger Kit Kat weighs 42 grams (1.5 ounces).
There is more weight in the wafer than in the chocolate.
In summary a medium-sized dog would have to consume several dozen "fingers" of Kit Kat before they would be at risk for poisoning.
For smaller dogs and if the Kit Kat was coated in dark chocolate instead of milk chocolate the figure would be slightly lower.
Once thats been established lets examine the problem ingredients in Kit Kats- cocoa butter and chocolate.