Generate TXT file with custom letter font

I am creating a code that generates a txt to print to a printer Matrix. However, I would like to change the font of the letters. Could anyone help me, please?

Follows the code below.

    try{

        byte[] bytes;

        using (MemoryStream memoryStream = new MemoryStream())
        {
            using (TextWriter textWriter = new StreamWriter(memoryStream))
            {
                string divisao = "=";
                for(int i = 0; i < 79; i++)
                {
                    divisao += "=";
                }
                foreach (eOA01 x in Lpdf)
                {                        
                    textWriter.WriteLine(divisao);
                    textWriter.WriteLine("ENDERECO= " + x.ENDERECO);
                    textWriter.WriteLine(x.PORTA);                      

                }

                textWriter.Flush();

                bytes = memoryStream.ToArray();
            }
        }

        Button3.Enabled = false;

        Response.Clear();
        Response.ContentType = "application/force-download";

        Response.AddHeader("content-disposition", "attachment; filename=OS" + DateTime.Now.ToString("dd/MM/yyyy") + "_" + DateTime.Now.ToString("HH:mm") + ".txt");
        Response.BinaryWrite(bytes);
        Response.End();
    }
    catch (Exception ex)
    {
        //porque ele está sendo usado por outro processo.
        string err = ex.Message;
    }

Thank you!