My fur baby

I have a 15 lbs chwinnie with an infection from a bad tooth and I don't have any money to take her to the doctor but I have some Cephalexin 500mg I looked it up to see if it was okay to give her some even though it says it's not a vets 1st choice but dogs can be prescribed it. The only problem I have is the it's a capsule and not pill form. Any suggestions on how much to give my baby girl