Is an RTM mandated by DoD or IAW DAU Principles? Right now we’re operating without one.
One of the tools in the Technical Management Processes is Requirements Management. A Requirements Traceability Matrix (RTM) ties all the program requirements to the items you are delivering and is especially beneficial if the requirements are not previously documented. The Chief Engineer will use the RTM as an approval mechanism during technical reviews or Configuration Control Boards.
The DoD Guidance found in 5000.88 (Engineering of Defense Systems) says requirements traceability is a requirement for all System Engineering Plans (SEPs), but it does not call out the RTM as the required format. Requirements Traceability will be part of the SEP unless waived by the MDA (I don't know if you have a SEP for the purchases you make at DLA). There is most likely documentation in your program's history when it was part of a MDAP which previously documented the requirements.
Below is a link to the RTM tool from DAU which will give you a template/guide for creating a RTM.
The tool below can will help you identify what documents will be required, or can be waived in any of the acquisition pathways. Under each pathway, click on the 'requirements' link and you will see the matrix of required documentation. If you are working in a Software Acquisition pathway it will clearly be different than a Major Capability pathway.
Finally, here is the link to DOD 5000.88. The journey of looking for the RTM starts with following the Systems Engineering Process. 5000.88 also references the Defense Acquisition Guidebook (second link) and chapter 3 gives details about how the Chief Engineer will use the RTM to support the SEP.