If you submit a proposal summary when you submit your proposal to the USG, does the FAR/DFARS require a Proposal Summary in the PO File?
Interesting question. It's hard for us to decipher acronyms like "PO file". That said, normally proposal summaries are not used for evaluation purposes and they should be nothing more than a summary of what is already in the contractor's proposal.
The contractor's proposal is not included in the resultant contract unless the USG incorporates all, or portions of the contractor's proposal when award is made.
The content of offeror proposals, not just the awardee's, that is required to be maintained in the official contract file can be found at FAR 4.803(a)(10). There is no DFARS implental or supplemental language regarding this topic or subject matter; nor does the DoD Source Selection Procedures Guide offer any amplifying guidance or policy on this subject matter.