exec command

[CJ Tres]

I'm trying to use the find and execute commands to remove *.html files 
in various subdirectories within a single directory but the command 
returns "missing argument to `-exec'

the command I've entered is:
find -type f -exec rm -rf"
followed by the path, followed by:
-iname '*.html'

Find alone has found all the files but I'm not understanding what is 
wrong with the syntax "-exec rm -rf"

Can someone see an obvious error?