autographed Gladys Knight & The Pips record

I picked up the gladys knight and the pips "i feel a song" LP and on the back is a personal message from singer of the group Edward Patten written in blue marker. It reads "To Janet, The best always, from Edward of Gladys Knight and the "Pips."  The record sleeve is pretty worn and the top is falling apart so someone unfortunately duct taped across it covering up the "To Janet" part of it. I have the disc with it and it is in good shape. I played it through and it crackles a bit but doesn't skip.

I'm wondering about how you check authenticity of this sort of thing and what the value may be.

Thanks!

Mike