Once you have created a template for the producer, you have to create a link to the producer. It can be a menu position. Navigate to Your menu:

Add a new position:

Click 'Select' on menu item type:

Select Single Producer View:

Now select the producer:

Click Save & Close:

Now navigate to the producer page on your front end. You will see that your template is assigned:

Now navigate to the builder panel in your yootheme:

You will see that there is an option to create a new layout:

You are now able to create a custom layout for the selected producer:

Example result: