A PMR format is typically organizationally dependent, but there are some good best practices and basic templates available.  Here is a listing of resources that may help in your PMR preparations.

Project Management Resource Tools (PMRT)
https://pmrt.altess.army.mil/pmrt/login.jsp?externalApp=cpe&refer=https://pmrt.altess.army.mil/portal/
-- Use the "PMRT Enterprise Analytics" application to find various tools and templates.  You'll need to register for an account.

IBR Toolkit:
https://www.secnav.navy.mil/rda/OneSource/Documents/CEVM/Tools%20and%20Examples/Navy%20Guides/CEVMIBRToolkitFinal20080319.pdf 
-- While not specifically for a PMR, this document has a lot of useful information and resources that can help.  See the Appendices for templates.

DoD Risk Management Guide:
http://acqnotes.com/wp-content/uploads/2014/09/DoD-Risk-Mgt-Guide-v7-interim-Dec2014.pdf 
-- Appendix C contains sample reporting templates for identifying risks, issues and opportunities

GAO Schedule Assessment Guide Best Practices:
http://acqnotes.com/wp-content/uploads/2017/07/GAO-Schedule-Assessment-Guide-Dec-2015.pdf 
-- Contains best practices for project schedules