I'm trying to create a new attribute that operates as a "lookup field" to another entity.
I've created an N:1 relationship from the "Another Entity" to my primary entity however I am unable to create a lookup field - its still only bit, int, decimal etc in the type options.
Clearly I am making a basic oversight here so help would be appreciated.
If you already created the relationship, you will find the attribute of the type lookup in the n-Entity. You can't / don't create it manually. It is named like specified in the definition of the relationship.