Canon PRO-100S series Online Manual page 106

5. Open the feed slot cover.
6. Slide the paper guides (E) to open them, and load the paper in the center of the rear tray
WITH THE PRINT SIDE FACING YOU.
7. Slide the paper guides (E) to align them with both sides of the paper stack.
Do not slide the paper guides too hard against the paper. The paper may not be fed properly.
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