Once Google Documents is opened, immediately save your document. Your document is then saved under your Gmail account. Type or upload your content, saving every so many minutes. To insert footnotes in a Google Document, at the end of a needed source click on Insert and scroll down to Footnote.
A text box will appear in the right side of the Google Document. Type the proper source citation or extra content needed for the footnote. When you are done writing the footnote, click outside the box and continue working in the main document. If you need to go back in the same footnote, click that footnote to continue typing.
To see how your footnotes will appear when printed, go to Print from the File Menu. You can also view your footnotes in PDF by going to the File menu.
If needed, for whatever reason, you can delete or hide your footnotes. To delete your footnotes, click on the footnote box, and choose delete footnote. If you change your mind, you can undo the delete by clicking the undo button. You can also hide your footnotes in the margin, by going to the view menu and select footnote.
To print footnotes as endnotes, go to File Menu, and select Print settings, under Annotations, click on "Print footnotes as endnotes" and uncheck the "Include Footnotes" box.
According to Google Docs (http://www.aresearchguide.com/7footnot.html), documents downloaded as PDFs will display footnotes at the bottom of the page (as when printed from Google Docs). Documents that are downloaded as Microsoft Word, OpenOffice, RTF and HTML files will display footnotes as endnotes, that is at the end of your document, rather than at the bottom of the page."