Formatting APS Journal Articles :: Credits Section
It takes time for a paper to be fully reviewed and accepted, and during the course of its revision process, important scientific breakthroughs may have been announced. Authors may want to include a brief paragraph stating that they are aware of these new discoveries and how their paper relates to the new information. This statement is included in the Recognition section as a Note Added in Proof and can be added only at proof stage.
Title the note added as "Note Added in Proof" as a level 1 header.
If you feel that the information detailed in the note greatly affects the subject matter of the manuscript, consult your fellow Copy Editors or Journal Supervisor. It may be that this necessitates another review of the manuscript, and the authors may have to revise their paper to include the new discovery.