I have a New Responsive Form. I set a field called Requestor with the Created By user. 

Requestor is set to Enforce Unique Values.

When a user clicks Submit it throws an error but it isn’t user friendly.

With InfoPath we did a count of IDs where the Requestors were equal then setting a field with the results. If that value was greater than 0 we hid the section holding the fields and showed a Section that said you have already submitted a request. 

I am trying to replicate this in the Nintex Form but can’t figure out a Rule Formula that will do this.