Vba range object single column autofill

Question

I'm attempting to automatically populate one range object's column. Eventually, I want to autofill using a formula. I tested this out using the below toy example. This results in a type mismatch error that I am unable to resolve.

Sub Macro1()
    
    Dim wk As Worksheet
    
    Set wk = ActiveWorkbook.Sheets("Temp")
    
    wk.Cells.Clear
    
    Dim rng As Range
    
    Set rng = wk.Range("A1:B5")
    
    rng.rows(1).Columns(1) = 1
    
    rng.rows(1).Columns(1).Select
    
    Selection.AutoFill Destination:=rng(1 & ":" & rng.rows.Count, "A")
    
End Sub

A vba newbie here. 

Answer 1

Just refer to the first column of rng. Change

rng.rows(1).Columns(1) = 1

rng.rows(1).Columns(1).Select
    
Selection.AutoFill Destination:=rng(1 & ":" & rng.rows.Count, "A")

to

With rng
    .Cells(1).Value = 1
    .Cells(1).AutoFill Destination:=.Columns(1)
End With

If you want to autofill from row 3 onwards:

With rng.Columns(1).Cells(3)
    .Value = 1
    .AutoFill Destination:=.Resize(rng.Rows.Count - 2)
End With