TracyJo said:
I don't think i would want to put penut butter on a door bell button
I would break this up into more steps. Get the dog to hit the button with it's paw, treat, and vocalize a command, let's say "bell". Get a solid response from the dog to hit the door bell to your command "bell". Then each time she's scratching at the door to go out, say "no" to the scratching, they command "bell" and as soon as she gets it to ring open the door and praise and give her the go outside command (if she has one already, my dog knows not to go outside a door unless I give it a release command).