Apple Personal LaserWriter300 - Manual (Page 21)

Loading 3-hole punched paper
Follow the instructions for loading ordinary paper, and position
the sheets as shown below.
Loading letterhead paper
Follow the instructions for loading ordinary paper, and position
the sheets as shown below.
Insert letterhead paper face down with the top
of the page at this end of the cassette. The holes should line up
along this side of the cassette.
Chapter 2: Adding Toner and Paper 13