Render HTML in RHTML

What you really need is your html file moved somewhere under app/
views, renamed to _htmlfile.rhtml and rendered as partial in your
rhtml template, like <%= render :partial => 'htmlfile' %> or
something. Possibly, but unlikely, I am missing some very unusual need
to keep things as you did, more detailed explanation would help make
things clearer. Don't try to provide abstract description, better try
to be as specific as it ever possible, or you'll get lots of answers
barely applicable to your case.