Place a rack in the middle third of the oven and preheat to 375 F. Evenly coat an 8 1/2 - by 4 1/2-inch (or similar medium-sized) loaf pan with nonstick spray. Sprinkle 2 teaspoons whole wheat flour in the pan. Tip it back and forth until the pan sides and bottom are coated. Reserve 1 more teaspoon flour for garnishing the loaf top
In a large bowl, thoroughly stir together the remaining whole wheat and white flours, 1 tablespoon seeds, Rumford Baking Powder, baking soda, and salt. In medium bowl using a fork, beat together the milk, yogurt, molasses, egg, and oil until very well blended.
Gently and gradually stir the milk mixture into the flour mixture just until thoroughly incorporated but not over-mixed; excess mixing can cause toughening. Immediately turn out the batter into the pan, spreading evenly to the edges. Garnish the top evenly with the remaining 1/2 tablespoon seeds, then dust with the reserved 1 teaspoon whole wheat flour. Using a well-greased sharp paring knife, make a shallow cut lengthwise down the center of the loaf.
Bake on the middle oven rack for 45 to 55 minutes or until well browned on top and a toothpick inserted deep in the center comes out clean. Let the pan stand on a wire rack for 15 minutes. If necessary, run a table knife around the pan and under the loaf edge to loosen it.
The loaf is best served fresh and slightly warm, but may be kept airtight at room temperature for a day or so. Freeze, airtight, for longer storage; thaw before using. If desired, reheat the loaf (wrapped in foil) for about 15 minutes in a preheated 375-degree F oven; or warm individual slices wrapped in paper towels for 20 or 30 seconds in a microwave oven on low power.