Previously, when posting an open invite, I have been able to state prefered rating of opponents in the game name.
This doesn`t seem to work anymore. When I put up 1400-1600, it doesn`t go up with the iinvite.
You can place your rating limits in the 'Game Name' field. This will appear on the far right side of the open invite games page. It lets people know what rating range you want to play against but does not actually enforce those limits. Anyone will be able to accept this particular game, whether they fall into your requested range or not.
You can also go to the 'advanced options' section and specify your rating limits and in this case only players who qualify for those limits will be able to accept the game. Those who are outside the range will not have a link to accept the game.
Both of these options have been around for quite some time.
edit..... I just created an open-invite game and used the 'game name' box to indicate my rating limits, and it worked fine.