This paper addresses a theoretical procedure for control of the contour mode excitation efficiency in thin piezoelectric arbitrarily-shaped resonators by adjusting the surface electrode configuration to the mechanical stress distribution. The procedure allows accurate determination of at least five efficiently excited modes for various electrode configurations. This is validated by experimentally measured data for rectangular resonators. For the first time, electrode configurations are suggested that provide high values of the dynamic electromechanical coupling factor for the longitudinal edge mode in a rectangular resonator, while the excitation of spurious modes is suppressed.