Workflow Custom Approver Rule

Hi All,

I am new to workflow development .

There is a requirement in my project to Have a custom approval logic in the workflow ( Finance accouting document approval) . For this I have already done the below :

1. Created a Z table

2. Created a function Module

3. Created a Rule through PFAC Transaction.

My question is:

How to assign this rule which has been created in the workflow definition ( Transaction - SWDD ) ?