How to check which installed package/ connected apps are using Self  signed certificate 

How to check which installed package/ connected apps are using Self  signed certificate 

Hello,

I currently have a custom object (example: customObject__c). This object is related to another custom object (example: customObject2__c). I would like to have my custom object have a new field lookup to a picklist field from the second custom object.

I was thinking about approaching this as a formula field and then have it return text. I'm not sure if I'm going about this the wrong way.

This is what I have so far:

TEXT(customObject2__r.customfield__c)

How may I approach this? Should I be doing this a different way? What are my options?

Sincerely,
Jackie