Specify a column as both a foreign key *and* a primary key?

When using the Information Design Tool to create a data foundation, it's best practice to specify the primary key in each table; it's also recommended that the foreign key be specified.

In a data foundation that contains a hierarchy of tables--where a table is a child of a table, and that child table is a parent of another child table, etc.--how can a column be specified as being the foreign key (in relation to its parent) *and* a primary key (in relation to its child)?

Also, does the IDT provide a means to specify a key that has multiple columns?