Brush grill rack with vegetable oil. Heat coals or gas grill for direct heat. Mix sour cream and brown sugar; set aside.
Cut frozen pound cake into 8 slices. On each side, sprinkle with rum, spread with butter and press almonds onto butter. Place cake slices on grilling screen.
Grill cake uncovered 4 to 6 inches from medium heat about 5 minutes, turning once, until golden brown. To serve, top cake with sour cream mixture