A signature? Who's? Oh, my god, it's Ron! Sure enough, signed with Santo's always great penmanship and with a nice "Best of luck" inscription.
It doesn't make much sense that this kind of signature with an inscription would have been obtained at the ballpark hanging over the wall with dozens of other fans. It wasn't. After Santo's retirement I sent some items including a rookie card to him at his Torco Oil office. I must have put this in a box with other scorecards and just forgotten about it. I'll bet I haven't seen it in decades.
The game was the second of a double header on June 27, 1973. The Cubs lost in 18 innings but Ron hit two game tying home runs, in the 9th and 13th. Some handwriting I had, huh? Here's the legible info on the game from Baseball-Reference.com. BTW Santo had a good first game too, which the Cubs won 6-1. For the day he was 6-11 with one walk, two doubles, two home runs, six RBI and four runs scored.