About
A foreign key repository join is used only to define a Primary Key-Foreign Key Relationships in the Physical Layer.
It consist of a column or a set of columns and refers to the primary key column in another table.
When you create it in the physical diagram, you have to point first the dimension and then the fact table.
When you import keys in a physical schema, the primary key-foreign key joins are automatically defined.
If you want to define other relationship, you have to use a complex join.
You do not create joins for multidimensional data sources.