Mac OS Excel vba error Run-time error 91 . Object variable or With block variable not set

Milto1850 I'm not sure why you are writing this code in a class module, as the hotkey assignment only needs to be done once in your Excel session, when the workbook containing this code opens. After that, pressing the hotkey will call the routine Hyperadd1 which already works on the active sheet. Also, you need to reset the default behavior of F11 when the workbook is closed. So remove your code and add this to the ThisWorkbook module of the workbook:

Option Explicit

Private Sub Workbook_BeforeClose(Cancel As Boolean)
    Application.OnKey "{F11}"
End Sub

Private Sub Workbook_Open()
    Application.OnKey "{F11}", "Thisworkbook.HyperAdd1"
End Sub

Sub HyperAdd1()
    Dim rng As Range
    Dim WorkRng As Range
    On Error Resume Next
    Set WorkRng = Application.Selection
    For Each rng In WorkRng
        Application.ActiveSheet.Hyperlinks.Add rng, rng.Value
    Next
End Sub