vb.net how to verify signature made by signdata

In this function:
- datatoverify - is data before signed ?
- signeddata - is data after signed
- key - is the public or private key

Function VerifySignedHash(ByVal DataToVerify() As Byte, ByVal SignedData() As Byte, ByVal Key As RSAParameters) As Boolean
        Try
            ' Create a new instance of RSACryptoServiceProvider using the
            ' key from RSAParameters.
            Dim RSAalg As New RSACryptoServiceProvider

            RSAalg.ImportParameters(Key)

            ' Verify the data using the signature.  Pass a new instance of SHA1CryptoServiceProvider
            ' to specify the use of SHA1 for hashing.
            Return RSAalg.VerifyData(DataToVerify, New SHA1CryptoServiceProvider, SignedData)

        Catch e As CryptographicException
            Console.WriteLine(e.Message)

            Return False
        End Try
    End Function