Use 33pF for C. The constant for R is determined based on an evaluation of your system.
For reference values, click the Group of your MCU below and refer to the standard characteristics.
4518 4519 4508 4509
4552 4553 4556 4559
However, keep in mind that the RC oscillation frequency characteristics listed in the user's manual are example measurements resulting from tests performed on our evaluation boards using standard samples. RC oscillation frequency is greatly affected by the parasitic capacitance of the evaluation board. Perform adequate frequency confirmation on the board of your application device before deciding on the final constant. (#105582)