See this Staff Resource page for how to write a Record Series Description in Archon: http://archives.library.illinois.edu/staff-resources/analog-workflow/how-to-write-record-series-description/.
If the born digital content is part of a hybrid collection, you will also want to create an “Electronic Records” or “Digital Surrogates” series as part of the analog series in the container list in Archon. See “Series 7” below under Detailed Description:
The Electronic Records series will contain a description of both the nearline and online versions as subseries, as well as a processing note explaining which tools were used to appraise and process the records in the Collection Content module. For example:
Make sure you mention the e-records in the Location(s) tab for the collection record, and include the size of the files in megabytes. For Location select "DIG: Electronic Records Repository"; for Content, write "e-records"; and record the number of megabytes of access files for Extent, e.g. "8860.44" and select "megabytes" from the drop-down box. See the William T. Greenough Papers for an example.
If the record series has a PDF folder and box listing, include this information as well. For an example, see the PDF folder/box listing for the Michael Stern Hart Papers.