I use seam-gen to generate a project using richfaces and FaceletViewHandler is placed in faces-config.xml. I think the right setup for a richfaces/facelets project is that FaceletViewHandler is in web.xml like this:
<context-param>
<param-name>org.ajax4jsf.VIEW_HANDLERS</param-name>
<param-value>com.sun.facelets.FaceletViewHandler</param-value>
</context-param>
