Currently, you must download the tool below to support Mac OS X. The tool is a third-party software which is a simple Notes DB app. It supports Notes (Standard) and Notes (Basic) running on Mac OS X, Windows and Linux. You can import Excel if you first save it as a CSV file, then use the “Import CSV (Comma delimited) button in the app. You can use the Lite (free) version, but for full features you need to purchase a license.
Video: Mail merge Excel to IBM Notes
https://youtu.be/nC-k4f0t7Ks
Print Merge Reporter (PMR) for IBM Notes - Mail merge Excel to IBM Notes:
https://www.notesmail.com/PrintMergeReporter