Rcm applicability on other than salary to a director

To an employee?

No, it is not applicable.

For what purpose if the amount paid to director? Bonus?

Bonus and salary are not charged under RCM if they are whole time directors.

Non executive, non whole time directors and outside directors are not employees of the company. So they will fall under RCM for salary, other charges received by them.

Bonus is the part of Salary So any bonus or salary is paid ,to whole time director  No RCM is applicable.(As per Schedule III)