Make sure that you place an ad in your local paper and put signs up with pictures of her on them. If you find your dog the person would have to give her back if you put a missing dog report in. Also let your local police department know. Most states have the 5 day rule. That means that after 5 days animal control can keep the dog. Good luck and I'm sorry about your situation.
I cannot believe someone would pick up your dog having identification and keep her. that is just awful. I cannot image what you are going through. all one day. i am so very sorry.
When you post, you might also want to mention that your missing dog is microchipped. If the thief thinks the dog is identifiable, he/she may give her back.
Also, be sure to let your vet know. I believe that a lot of vets will pass the word when a microchipped pet disappears. If your dog shows up at another vet's office, they may be able to identify.
Also , make sure you post that she was seen being picked up by someone in a pick up truck. If they know they were seen getting her, maybe they'll have second thoughts about trying to keep her.