Don't. It's rude to ask your guests to provide food for your event. Please take care of your guests properly by providing the food yourself by managing your budget properly and not being selfish.
'Find out how much money you can spend per guest on food at the
reception, and use that amount to determine the number of guests you can
invite. After all, the head count at your reception is the biggest
expense in your wedding budget. Establish your budget, and stick to it.'
Do not invite a ton of guests you cannot afford to feed and do not splurge for a designer dress and then expect your guests to feed each other. A potluck wedding reception is completely rude. Don't do it.
*Added note: Your reception is a thank you to your guests not a party just for you.