Rub potatoes with oil; sprinkle with 1/4 teaspoon salt. Place potatoes on a jelly-roll pan coated with cooking spray. Bake at 400° for 35 minutes or until tender. Remove from oven; cool 10 minutes.
Cut potatoes in half crosswise; cut off a small portion of the rounded edge so the potato will stand upright. Carefully scoop out about 1 teaspoon pulp from each half, leaving the shells intact. Combine potato pulp, milk, butter, pepper, cheese, and remaining 1/4 teaspoon salt in a bowl. Spoon about 1 heaping teaspoon potato mixture into each potato shell. Arrange stuffed potatoes on a jelly-roll pan; top each with 1/2 teaspoon chopped salmon. Bake at 400° for 15 minutes or until thoroughly heated.