How much dried rosemary do you use when the recipes calls for fresh rosemary?

Usually about three times as much, but if a recipe calls for fresh, do your best to use fresh. Dried rosemary is one of those herbs that does not do very well dried. Fresh vs dried makes a huge difference.

Also, depending on the recipe, if you're using dried rosemary, don't leave it in the food. Let it sit to soak the flavor in and then strain/take it out.