A footnote is a brief note that provides additional content or copyright attribution. Any type of paper may include footnotes. They are not used for references in APA style.
For further information see the APA Manual p. 40.
Appendices can be used to supplement the paper's content. Include an appendix only if it helps readers understand, evaluate or replicate the study or theoretical argument.
Appendices are added after the reference list.
For more information see the APA Manual p. 41.