Within Diligent Respond, click on the Document link from the main navigation panel on the left.  From there, click the + Add button.

Add the desired document and click on the + Add optional segments at the bottom of the image below.

Select the desired segment and child segments that you have defined (https://support.diligentpharma.com/hc/en-us/articles/44218774128147/live_preview/01K3PN34KNXR1TRAT4M2B5XTK3).  In the example below, we have selected the Region segment and specifically the US location.  

When a RFI is requested you can select the desired knowledge segment and your appropriate documents and answers will be searched.