Adding functional module in MSMP workflow

Hello,

I have copied GRAC_NOTIF_VAR_RULE_AR standard function module into Z to add role description in GRAC workflow but I do not know to do configuration for the same. I know I need to add this Z FM in step 2(maintain rules ) in MSMP workflow configuration but how to link process initiator to this.

Can anyone let me know the steps for this.

Thanking you.