When you tap on the Add a Meal button (the middle one at the bottom of any page in the app), up to 60 restaurants/food establishments closest to your current location are listed. If the restaurant you are looking for isn't listed, tap in the box labeled "Restaurant Name" at the top of the page. Enter the name of the restaurant you are looking for, and then tap the blue Search button on your phone's keyboard. If the restaurant isn't very close to your current location you can also specify a location in the next box. For example, if you live in New York but want to rate a meal that you had while on vacation in San Francisco last week, just enter the restaurant's name and then "San Francisco, CA" in the location box.
It is possible that the restaurant you are looking for may still not be listed. This list comes from Google, which means that anything that you can find via Google Maps should, in theory, be available in PlantEaters. If this isn't the case, please let us know and we'll try our best to get Google to add the restaurant in question.