Add the dried herbs to a food processor. Alternately, you can place them in a small bowl and use a mortar and pestle to crush them by hand.
Pulse (or crusthe spices together until the desired texture is reached. The main goal is to break down the dried rosemary into smaller pieces, but aside from that you aim for flakes or more of a powdery spice consistency.
Use immediately or store at room temperature in an airtight container. Homemade Italian seasoning will keep indefinitely, but it will start to diminish in flavor after 6 months.
Notes
Total yield: 1/4 cup + 2 1/2 tablespoons (approximately)