Apologies you’re ticket hasn’t been answered. I’ve taken over the support forum as of today, so I’ll be monitoring responses going forwards.
The theme required the Cart66 plugin, you’ll need to download this (it’s free) from the WordPress Plugin repository. Instructions can be found here – http://www.redfactory.nl/themes/therestaurant/2013/02/27/cart66/
I’ve checked your site and your menu is showing as a drop down, have you managed to resolve this since posting?