次の操作を行うマクロの構文を教えてください。

下記のコードが素朴な書き方です。

一行目から、空白のセルにあたるまで繰り返し処理します。

処理速度を考えていない書き方なので、行数が数千行を超えると遅く感じるかもしれません。

Sub main()
    
    Dim Rng1 As Range
    Dim Rng2 As Range
    
    Set Rng1 = Sheets(1).Cells(1, 1)
    Set Rng2 = Sheets(2).Cells(1, 1)
    
    size1 = Rng1.CurrentRegion.Rows.Count
    size2 = Rng2.CurrentRegion.Rows.Count
    lastRow = size2
    
    For i = 1 To size1
        
        found = False
        For j = 1 To size2
            If Rng1(i, 1) = Rng2(j, 1) Then
                found = True
                Exit For
            End If
        Next
        
        If Not found Then
            lastRow = lastRow + 1
            Rng2(lastRow, 1) = Rng1(i, 1)
        End If
        
    Next
    
End Sub

こうやってこうやってこうだ!!（意味不明WW

Sub settest()
    For a = 1 To 65536
        Debug.Print Worksheets("Sheet1").Cells(a, "A")
        If Worksheets("Sheet1").Cells(a, "A") = "" Then Exit For
        If Worksheets("Sheet2").Range("A1:A65536").Find(Worksheets("Sheet1").Cells(a, "A"), LookAt:=xlWhole) Is Nothing Then
            Worksheets("Sheet2").Range("A1").End(xlDown).Offset(1, 0) = Worksheets("Sheet1").Cells(a, "A")
        End If
    Next a
End Sub

A列のみやってます。