test.cs

using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl())
{
    tx.Create();
    // load the document
    tx.Load("template.tx", TXTextControl.StreamType.InternalUnicodeFormat);

    // merge the data
    using (MailMerge mm = new MailMerge())
    {
        mm.TextComponent = tx;
        mm.MergeObject(xRechnung);
    }

    // save the document
    tx.Save("test.pdf", TXTextControl.StreamType.AdobePDFA, saveSettings);
}