<p>In this study an analytical study of thermoelastic damping in piezothermoelastic fiber-reinforced composite (PTFRC) Kirchhoff plate resonators considering size dependency is carried out through generalized heat conduction. Effective characteristics of the composite medium are computed based on a combination of rule of mixture (RM) and strength of materials (SM) approach; thereby the coupling of the mechanical-electromagnetic and thermal characteristics of the PTFRC can be realistically modeled. Modified couple stress (MCS) theory and dual phase lag (DPL) conduction are employed in formulating the governing equations. Based on numerical calculations, the influence of various factors like fiber volume fraction, phase lags, and size dependency on the damping effect and frequency shift of the composite can clearly be observed. The potential to optimize the dynamics behavior of the composite through careful material design can be inferred from the current findings. The proposed approach offers a strong base for application oriented studies in multifunctional composites and may prove to be useful in developing smart sensors, micro/nano electromechanical systems (MEMS/NEMS) resonators, energy harvesters, and other adaptive structures.</p>