Heat the oil and 2 tablespoons of the butter in a heavy 12-inch skillet over low heat. Season the pork chops with 1/2 teaspoon salt and 1/4 teaspoon pepper and then dredge them in the flour.
Increase the heat to medium high. When the flecks of milk solids from the butter begin to turn golden brow , put the pork in the pan. Saute, turning once, until golden on both sides and just cooked through, 6 to 7 minutes total. Transfer the pork to heated plates. Return the skillet to medium-high heat. Add the orange juice, Dijon, and rosemary. Boil rapidly until the liquid reduced to about 1/4 cup. Tilt the skillet so that the reduced liquid is at one side of the pan and whisk in the remaining 1 tablespoon butter. Taste the sauce and adjust the seasoning as necessary. Spoon the sauce over the pork and serve immediately.