Sure you can add more holes :) But there are adjustable cat collars - eg size 8" to 12" that may fit him and have holes that won't fray already in place. Lupine brand collars come in this size.

Is it a nylon collar? If so, take something metal and pointed, like an ice pick or a skewer, heat it over a flame and then burn a hole into the collar. Mark the area you want the hole before starting the process.

With a cat collar you just need to make sure you don't make the hole too large or the latch may not hold well. Another option is to try a hole punch with a small hole size, then burn the edges to keep them from fraying.

Cynthia, I like the collars that allow for them not being able to choke themselves and I couldnt' find them in adjustable so that is why I had my problem.

Does this cat go outdoors?

If not, what is the benefit of a collar?

The benefit of a collar for indoor cats is that if something happens (escape, fire, break-in, accident on the way to the vet) the cat has id. All animals should wear id in the house.