When you first arrive in Hill Valley 1931, you will encounter a younger version of the nosey old lady. After the conversation, head towards the police station. When the camera angle changes for you to cross the street, head back to the left and look at the sign for the Law Offices of Gale, Zemeckis, & Fine to unlock this achievement.
* Bob Gale and Robert Zemeckis wrote the screenplays and also Robert Zemeckis directed the Trilogy. I take it that Mr. or Mrs. Fine is one of the creators of the game.
To learn more try out these links: