I found following information about S08RN trimming but I have some question were I'm not 100% sure and if my understanding is correct:
1) Factory reserved memory location is not accessible (read/write) by user?
2) The conventional location at 0xFF6E is blank 0xFFs when part is shipped?
3) If conventional location 0xFF6E is used the user SW must read it and write it to ICS_C3?
"For S08RN, All MCU devices are factory programmed with a trim value in a factory reserved memory location. This value is uploaded to the ICS_C3 register and ICS_C4 register during any reset initialization. That means you don't need to initialize ICS_C3 in your software.
However, if you want to use other trim values, the conventional location is 0xFF6E-0xFF6F, P&E tools will program new trim value in those addresses.
By the way, the RN60 factory trim value is 39.0625 kHz"
Thanks for your help