When writing a research paper in the social and behavioral sciences, you may have supplementary information that does not fit well within the body of your paper but adds helpful information for a reader, such as survey documents or results graphs. That information belongs in an appendix. The APA formatting for appendices varies depending on the information you are providing, but some general guidelines apply.
According to the 6th edition of the "Publication Manual of the American Psychological Association," the title "Appendix" appears centered at the top of the page. Label multiple appendices separately with "A," "B" and so on following the title and reference the material in your text accordingly, such as "See Appendix B." Each appendix begins on a new page in the document. An appendix may include headings and subheadings if it helps the reader understand the information within. Information within the appendix taken from outside sources must still include acknowledgement through signal phrases and/or parenthetical citations. All text in an APA style paper is double-spaced, including any appendices. The running head continues on all pages, including any appendices. Place the appendix after the References page or pages but before any tables, figure captions and figures.