When you open a Simulink® model that does not have internally stored requirements links, the RMI tries to load requirements links from an .req file, either the default file, or a previously specified file. If that file does not exist, the RMI assumes that this model has no requirements links.
To explicitly load requirements links from an external file:
Select Analysis > Requirements Traceability > Load Links.
The Select a file to load RMI data dialog box opens, with the default file name or the previously used file name loaded into the File name field.
Select the file from which to load the requirements links.
Click Open to load the links from the selected file.