Function SheetExists(shtname As String, Optional wb As Workbook) As Boolean

Dim sht As Worksheet

If wb Is Nothing Then Set wb = ThisWorkbook
On Error Resume Next
Set sht = wb.Sheets(shtname)
On Error GoTo 0
SheetExists = Not sht Is Nothing

End Function


Sub macro()

    Dim xRow As Integer
    Dim xCol As Integer
    Dim MyRange As Range

    Set MyRange = Sheets("Dataset").UsedRange
    xRow = MyRange.Rows.Count
    xCol = MyRange.Columns.Count


    If SheetExists("Summary") = 0 Then
        Worksheets.Add
        ActiveSheet.Name = "Summary"
    Else
        Sheets("Summary").Select
    End If


    Range("A1").Value = xRow
    Range("A2").Value = xCol


End Sub