Thanks for the additional information.
The toxicity of chocolate is judged by the amount of theobromine in it. Milk chocolate (like the kind in candy bars), contains 60 mg per ounce of theobromine. The toxic dose is one ounce of milk chocolate per pound of body weight. For example one pound of milk chocolate is poisonous to the nervous system of a 20-pound dog. If you figure it all out, it ends up being that it takes 2-3 chocolate bars to be toxic to a 10 pound dog.
Obviously your dog didn't get anywhere near that amount, so I'm not so worried about it.
If this were me, I'd just keep an eye on her for problematic symptoms. The symptoms of chocolate toxicity include trembling, nervousness, shaking, increased heart rate, panting, and, worse case scenario, seizures or death. Dogs that eat dark baker's chocolate squares are at most risk of seizuring or dying from chocolate.
I don't expect to see any of these issues because she really did consume a small amount of actual chocolate though.
I hope this helps.