Try this
Sub Table_Insert()
    
Dim LastColumn As Integer


    ActiveSheet.ListObjects("Table1").ListColumns.Add
    
    LastColumn = ActiveSheet.ListObjects("Table1").Range.Columns.Count
    
    ActiveSheet.ListObjects("Table1").HeaderRowRange(LastColumn).Select
    
    ActiveCell.FormulaR1C1 = "CLIENT NAME"
    
    ActiveCell.Offset(1, 0).Select
    
    ActiveCell.FormulaR1C1 = "=TRIM(UPPER(SUBSTITUTE(R[0]C[-13],""."","""")))"
    
    ActiveCell.Columns.EntireColumn.AutoFit

End Sub