Click on Settings (cogs icon) in the Toolbar and Edit Macros.
In the header.tex file, insert these lines:
Go back to your document, and in the place where you want the supplemental information section to begin, insert the following LaTeX snippet:
Export your document and enjoy labels as S1, S2, etc.
Please note you can change the S to anything (e.g. A, for Appendix) by modifying the snippet in the header.tex file.
Published on: 12 / 12 / 2017