Drupal Commerce. Trigger shipping rules based on product field value I'm really losing the will to live and hope somebody can help me.

I want to trigger a 'free shipping' rule based on a product field value, but for the life of me can not expose the free shipping field to rules. 

I have read about bringing items into scope and have created a component which has access to the field. But when I attempt to add the component as a condition of my rule I am prompted to enter data selector -  none of which seem to lead anywhere. I think it was wanting a product ID, which does not make any sense to me.

What am I doing wrong?



MORE BACKGROUND

I have tried two scenarios, one of which is to create a shipping rule,based on the conditions below. The other is to create a component, as described above

Condition1 - Entity has field > Parameter: Entity: [commerce-order], Field: field_free_shipping

Condition2 - Date value is empty (also tried data comparison) > However this does not lead me to the field stated in Condition1
I eventually managed to get this working by dropping the idea of having custom fields and replacing them with taxonomy terms. For whatever reason (probably inexperience) I could not expose my custom fields to the rules module in order to trigger the shipping rules that I wanted.

By leveraging the Commerce Rules Extra module I was able first to trigger my shipping rules based on taxonomy terms instead of custom fields and secondly to define additional conditions for firing these rules with the help of the modules maintainer @MarcElbichon as discussed here https://drupal.org/node/2087815