Call ShowHelp to submit a keyword-based Help request. By default, the RTL Help System gives the request to the first Help Viewer that claims to be able to handle it. Typically, the Viewer passes the Help request to an external Help engine, which displays a list of matching topics (if more than one topic matches) or goes directly to a specific topic (if a single topic matches). 

To support keyword-based Help requests using multiple Help Viewers, assign a Help Selector, using the AssignHelpSelector method.