Heat a grill to high heat.
In a small bowl, combine the salt, pepper, rosemary, and garlic powder.
Brush the steaks with olive oil.
Sprinkle the rosemary mixture over each side of the steaks to coat evenly.
Grill for 4 to 5 minutes on each side for medium-rare. Remove from heat and let rest for 5 minutes.
Top each with a pat (1 to 2 teaspoons) of butter and serve.