Yes, there really was a newsstand comic book devoted to the McDonald's clown mascot. Charlton won the right to publish the character's fictional adventures (probably just by being the lowball bidder) and managed to crank out four issues. Kids must not have cottoned to the title without the smell of beef tallow to coax them.
Issues 1 and 3 were reprinted for exclusive distribution at McDonald's restaurants; these had the phrase 'Not For Resale' on the cover.
Fun fact (not really): TV weatherman Willard Scott played the original version of Ronald on the first TV commercials to introduce the character.