This work reports on the procedure of Resonant-LIBS, where an OPO laser is fine-tuned to the resonant transition (W I) followed by optical emission spectroscopy. Compared to conventional LIBS, the ablation rate is significantly reduced in the resonant regime, resulting in finer resolution of depth profiles. This reduction in ablation rate can be attributed to a process called Resonance Laser ablation (RLA) where a part of the laser energy is employed for ablation, while the rest is dedicated to resonant excitation. The sample under consideration is a WTa-coated (7µm) Mo substrate prepared by dual magnetron sputtering system. These efforts are motivated by the need of improvement of quantitative depth analysis of W based plasma facing components (PCF). Particularly to target the undesirable surface modifications due to the interaction with H isotopes in fusion plasma, such as fuel retention or erosion/deposition.