It's rather trivial but the maintainer asked me to provide a patch nonetheless since we got no reply from upstream. See attachment.
-- -- Andreas :-)
--- postfwd-1.35/sbin/postfwd 2013-04-18 22:31:23.000000000 +0200 +++ postfwd-1.35-bug749485/sbin/postfwd 2014-10-15 11:25:21.712460389 +0200 @@ -1572,7 +1572,7 @@ my($index,$now,$mycmd,$myarg,$myline,%request) = @_; my($myaction) = $default_action; my($stop) = 0; my($ratetype,$ratecount,$ratetime,$ratecmd) = split "/", $myarg, 4; - my($rcount) = ( ($mycmd =~ /^size/) ? $request{size} : (($mycmd =~ /^rcpt/) ? $request{recipient_count} : 1 ) ); + my($rcount) = ( ($mycmd =~ /^size/) ? ( $request{size} * ( $request{recipient_count} || 1 ) ) : (($mycmd =~ /^rcpt/) ? $request{recipient_count} : 1 ) ); if ($ratetype and $ratecount and $ratetime and $ratecmd and $rcount) { my $crate = $Rules[$index]{$COMP_ID}.'+'.$ratecount.'_'.$ratetime; if ( defined $request{$ratetype} ) {