How do I set it up Custom Conversion Rule?

1. Create your fields manually in the object where the rule will apply:
   • A Picklist/Text field for the custom currency ISO Code (e.g. “Custom_Target_Currency__c”)
   • A Number field for saving the computed exchange rate (e.g. “Custom_Exchange_Rate__c”)
2. Go to the Currency Updater Setup Page (tab or VF page).
3. Add or edit a Custom Dated Exchange Rate Rule, and complete these two new values:
   • Custom Conversion Target Currency Field: the API name of the field that contains the custom ISO code (e.g. Custom_Target_Currency__c)

Custom Conversion Exchange Rate Field: the API name of the field where the custom rate will be stored (e.g. Custom_Exchange_Rate__c)