This test illustrates the difference between rotoscoping and reference. Snow White and most Disney features have live action film as reference but the styling and proportions of the characters make it impossible to call them rotoscoped. Rotoscoping is the verbatim tracing of live action footage as can be seen in the still images from Don Bluth’s “Thumbelina” posted below.
Other animated films with heavy rotoscope are Fleischer’s “Gulliver’s Travels”, and Ralph Bakshi’s “Lord of the Rings”.
Update: For some reason many of my early Youtube videos don't play all the way through anymore. Sorry for the inconvenience but it's out of my control.
Live action reference rotoscoped
Rough animation of Anthony by Joel Brinkerhoff using Flash
Live action footage and rotoscope from Don Bluth's "Thumbelina"
UPDATE: A sequence of reference for the Disney version of Alice in Wonderland was discovered and put beside the animation to show how much of the performance was altered by the animators. Here it is: