To prevent fringing fields from the power plane coupling to the edge of the board or radiating outward, the suggests making the power plane physically smaller than the ground plane by 20 times the dielectric thickness between the layers. This pushes the edge radiation away from the board boundary.
No article is complete without a checklist. Use this sequence during your next design. To prevent fringing fields from the power plane
Keep signal and return paths as close as possible. To prevent fringing fields from the power plane