I think it's real but I do understand your concerns.
Baseballs aren't easy to sign and as Reagan got older and less well his handwriting suffered. The second R is affecting the look of the signature, but there are no letters that are warning signs to me.
Hi Dr. Loomis. I rarely buy something like this without talking to a friend or two who knows the autograph well. Especially at auction because there is usually no return privilege.
I like the nice, creamy ball and bold signature. If I collected Reagan I'd be happy to put this in my collection. Others could have different opinions though.