Thank you all for your suggestions and concern. After calling five local vets who wouldn't see chickens, I called the Hattiesburg Vet Clinic (the avian vet) to talk to them about my problem. The on-call veterinarian (who is not the avian vet) said if I could be there by noon, she could give me a tutorial. So, off I went with Debbie in tow! Two hours later, we were there.
After feeling the lack of breast tissue, the on-call vet was also stumped about where to give the injection. She called the avian vet. He instructed her and we pressed on. An assistant held Debbie like a baby with her stomach exposed and head up ... at about a 45 degree angle. The veterinarian sprayed the area surrounding her keel bone (below the crop) with a water bottle. She was able to separate the feathers to find the skin. She then injected the medication right beside the keel bone at a slight angle into the small bit of muscle that was there.
Now for the fun part ... she said, "It's your turn." She put a small bit of saline in the syringe and told me to "go for it." For easier penetration, she instructed me to angle the needle so that the longer end of the tip was closer to her skin. Although I didn't want to stick Debbie again (she didn't seem to mind too much) and I thought I might faint, I forced myself to do it. And, guess what??? I DID IT!!! Twice!!! Poor Debbie, although I think she actually slept through some of it.
My husband and I will do this on our own later tonight. Wish us luck!! Oh, I have been driving ALL day ... and making multiple stops to feed myself and Debbie. I'm tired. I'll post pictures of the insertion site tomorrow. This may be helpful to squeamish novices like me who need to give a skinny chicken a shot.
#TeamDebbie