INSTALL

Copy the appropriate version of RVView.dll to the "Viewers" subdirectory of the DOpus directory.
32-bit RVView.dll is in Bin\Win32 directory.
64-bit RVView.dll is in Bin\Win64 directory.
By default, the target directory is "c:\Program Files\GPSoftware\Directory Opus\Viewers".

Run Directory Opus.
Open its Preferences window. 
You can do it from a lister window (menu "Settings|Preferences")
-- Or --
You can do it from the Directory Opus icon on the Windows taskbar. Click the icon, choose "Preferences" in the menu.
Open "Viewers|Viewer Plugins" page. You should see "RVF File" in the list. If you do not see it, click the "Refresh" button.

UNINSTALL

Close Directory Opus.
Delete RVView.dll.
Delete all other unpacked files of this viewer.