What expression to use for Prohibit User Self-Approval to skip the initiator when delegation is used

Summary:

Hello,

I have the following scenario:

Nathalie submits the  unmatched invoice which is less than 100.000 euro, the threshold is a rule selection criteria

2.The invoice should go to Aurelien using the workflow rule --- Aurelien has a delegation to Nathalie and at this point the system should skip the first approver as it is the same as the submitter (Nathalie).

3. The next approver should be Patrick according to the system rule.

I have tested the following Oracle note How to Prohibit Self-approval For Invoice Creator? KB79907 but I was not successful as the invoice is in error with no explanation.