Many of my projects are located in Michigan and in Michigan International Feet is the preferred unit of measurement when using NAD83. However, when Calculating Geometry the International Foot unit IS NOT included in the units drop down. If I recall correctly it was included in previous versions before version 9. You may think that using an International Foot coordinate system may default the "Units: Feet US [ft]" to international feet, but it does not and I have had this field verified by a licensed surveyor. The only way to correctly calculate the international units is to use ADD XY which for some reason doesn't work very well in 10.4.1. ArcCatalog often freezes and every single time I must refresh the geodatabase or it will error out. Any ideas or is this just the way it is for now?
Unfortunately, it's not planned to update ArcGIS Desktop with both feet versions. Desktop uses a restricted list of units and there's no plans to change that.
Another alternative might be to use the Field Calculator if the data is already using international feet. ArcGIS Pro is much more flexible when it comes to unit-handling.
Is there some reason this option was taken out of ArcGIS? All the border states typically have to deal with International Feet at some point or another. In Michigan International Feet is the official unit.