To add a table valued function call, in Catalog Explorer right-click the catalog, schema or Table Valued Functions node and choose Create Call Definitions to Table Valued Functions. This will bring up the Reverse Engineering Element Editor with the Table Valued Functions to which you can specify a call definition and as well select the return type, which will be mapped onto the resultset.
You can also select one or more individual table valued functions, right-click and select Create Table Valued Function Call Definitions which will bring up the Reverse Engineering Element Editor.
The designer also offers a General Table Valued Function Call Editor. This is a special kind of Table Valued Function Call editor which allows you to edit the table valued function call which is currently selected in the project explorer. This editor is opened by selecting Project -> General Table Valued Function Call Editor in the menu, or by clicking the button in the toolbar.
The advantage of the General Table Valued Function Call Editor is that it keeps the current sub tab selected when you select another table values function call in the project explorer, which allows you to e.g. edit the mappings of several table values function calls without a lot of clicking through tabs.