Automatic Reconciliation for Clearing Account is not working as excepted

There are some eligible transactions to reconcile but when we run the automatic reconciliation for clearing accounts the transactions are not reconciled.

https://docs.oracle.com/en/cloud/saas/financials/24d/faugl/what-s-the-difference-between-reconciling-clearing-accounts.html
https://community.oracle.com/customerconnect/discussion/693035/how-to-setup-reconciliation-reference-for-reconcile-clearing-accounts-automatically-feature

As per these documents we came to know - Reconciliation reference is required for Automatic reconciliation.

But we haven't found any document to setup the reconciliation reference for journal lines, could you please suggest.