The District Line and the North London Line depart from different platforms, however they share tracks from here to Gunnersbury. South West Trains serve different platforms again.
(Note that this station does not serve Richmond, North Yorkshire).
External links
Richmond station timetable (http://www.livedepartureboards.co.uk/ldb/summary.aspx?T=RMD) from National Rail's Live Departure Boards
Street map (http://www.multimap.com/map/browse.cgi?client=public&db=pc&addr1=&client=public&addr2=&advanced=&addr3=&pc=TW91DL&cidr_client=none) of Richmond station, from multimap.com