By playing with F# and ArcGIS Runtime I tried to re-create a sample C# project to F#.
For the WPF part I used the Visual Studio extension F# Empty Windows App (WPF) and F# Windows App (WPF, MVVM) the NuGet packages FSharp.ViewModule.Core and FsXaml for WPF.
The XAML I copied more or less without changes to the F# project.
During running the app it immediately crashed with an error:
Additional information: 'Cannot create unknown type '{http://schemas.esri.com/arcgis/runtime/2013}MapView'.' Line number '12' and line position '10'.
Why ever here it needs an additional hint for the esri namespace to resolve the control:
xmlns:esri="clr-namespace:Esri.ArcGISRuntime.Controls;assembly=Esri.ArcGISRuntime"
And voila – the F# ArcGIS Runtime app showed up
btw: the designer was not complaining anything and displayed the control as expected.