John Goodman can carry a film but he needs better material than King Ralph. Ralph becomes the next-in-line member of the English royal family through death of the entire royal family. He is unbelievably lacking in knowledge of royalty, and believes he has been offered a "job" and can only be coached into taking the position when he learns everything is free.
Peter O'Toole is very effective as chief secretary and coach for the new king of the Commonwealth. O'Toole has his hands full keeping Ralph away from an attractive young commoner whom Ralph falls in love with. There is also a battle to keep a ambitious Lord from taking over the throne.
Not to mislead, the film does have some enjoyable moments; a princess who looks delicate and has a voice like Yul Brynner, Ralph's leisure suits, clumsy antics at the dinner table and his general irreverence at being royal. Most enjoyable, however, is watching Ralph the First perform The Duke of Earl with his new group at the end of the film. This is not a bad film -- Goodman is fun to watch, but a better script would have helped a lot.