Ronald Reagan "vista dori" ride to raise money for boys and girls club

Did Ronald Reagan ride horses in the "vista dori" ride in California to raise money for the boys and girls club? I have a picture of my grandfather and other Cowboys ( someone them actors)with Ronald Reagan at one of these events. I have several cowboy hats with the "stamp" on them a different stamp each year ! The stamp is an ink stamp of a horse leading a donkey or pulling a wagon ect that was stamped on their hats for the ride! I want to know if the picture is real! On the back of picture is written 1990 ! My mother just gave this to me!