For humidity you can spray down his enclosure with a spray bottle. Redfoots are rainforest tortoises so feel free to be extra generous when spraying. If you don't have the time to spray his enclosure a few times every day, I guess you'll need a humidifier. I do not recommend sealing off the top of the enclosure. A lot of people make the mistake of completely sealing off the enclosure to keep in humidity but the air quality gets horrible as a result.
As for food, romaine lettuce and pumpkins are great sources of food. If you want to find more types of food in your area that your tortoise can eat I'd suggest using the tortoise table.
Romaine is not a good food source and Redfoots have such a wide variety of food on their menu, there is no need to recommend something like that...