Since residual vibration decreases lifetime of springs in the system, the profiles of spring-loaded cam and cam follower are important design factors of cam mechanism in automation machineries or engines. By simplifying the vibration by modeling it as a 1DOF oscillator, trajectory of cam follower, called pitch curve, affects the oscillation by modifying enforced displacement of the oscillator base. Although both profiles of cam and cam follower influence the pitch curve, people usually consider merely cam profile and ignore the effect from the shape of cam follower. In this report we study the effect of radius of roller follower, which contacts a periodical sinusoidal translation cam. In case the radius is smaller than the amplitude of the cam profile, almost sinusoidal enforced displacement can excite merely a resonant condition in the oscillator. However, in case the radius size cannot be ignored against the amplitude of the cam profile, higher harmonics excitations, especially 2nd harmonics, also occurs in the oscillator. Hence the radius of cam follower affects harmonics of cam mechanism, we should consider the trajectory of pitch curve as the combination of cam and cam follower profiles in design them.