Place a pizza stone on the bottom rack of the oven and preheat to 450°F.
Stretch and roll out your pizza dough on a floured work surface until as thin as possible without tearing. You should get about a 12-inch circle. If the pizza dough springs back, cover it with a clean kitchen towel and let it rest for 10 minutes before continuing shaping. Transfer the pizza to a parchment lined pizza peel or flat cookie sheet.
Brush pizza dough evenly with the olive oil. Top with the goat cheese, onion, and prosciutto. Sprinkle with the rosemary and vinegar. Season to taste with salt and pepper.
Bake the pizza for 10 minutes, or until the edges of the crust are golden.