If you want to calculate the excitation force from the acceleration you can apply the newtons law F= m a with m is the mass and a is the acceleration. If the force is sinusoidal, the a acceleration will be also sinusoidal.

Here, it is assumed that the frictional force is negligible and also there is no restoring or spring force. If they exist and affects the motion one has to take them into consideration such that F- Ffrec -F rest= ma.

Best wishes

Thanks a bunch Mr. Zekry for the answer. I am actually working on that.

Good day and God bless!