CTOF@CLAS12 plastic scintillator counter was tested with proton beam at Korea Institute of Radiological and Medical Sciences (KIRAMS). The counter have been designed and constructed as a plastic scintillation bar coupled with the 1.5 and the 2 inches of diameter fine mesh photomultiplier tubes (FM-PMTs). The dependence of the TOF resolution on the light output has dened. Obtained results of the 1.5'', 2'' FM-PMTs' timing and gain performances in magnetic eld confirm their suitability for precise particle identification in the CLAS12 future detector.