VBA Code To Split The Last Letter

I am looking for a very simple thing. A VBA code to split last letter of a column to the column after (offset 1). For ex. if K column contains "SEKWPRTY6" then "6" should be in L column and "SEKWPRTY" should stay in K column still. I tried this code but it gives "Invalid procedure call or argument"

VB:

Sub SplitAvail()
Dim rng As Range
For Each rng In Range("k1", Range("k" & Rows.Count).End(xlUp))
rng(, 2).Value = Right$(rng.Value, 1)
rng.Value = Left$(rng.Value, Len(rng.Value) - 1)
Next
End Sub