DouKaku?

using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
class Program {
    static void Main(string[] args) {
        string s = "Hello, world!";
        Document doc = new Document(PageSize.A4.Rotate(), 0f, 0f, 0f, 0f);
        PdfWriter.GetInstance(doc, File.Create("hello.pdf"));
        doc.Open();
        Font f = FontFactory.GetFont(FontFactory.TIMES_BOLD);
        f.Size *= doc.PageSize.Height / 
            (f.BaseFont.GetAscentPoint(s, f.Size) - f.BaseFont.GetDescentPoint(s, f.Size));
        Chunk chunk = new Chunk(s, f);
        chunk.SetTextRise(-f.BaseFont.GetAscentPoint(chunk.Content, f.Size));
        chunk.SetHorizontalScaling((doc.PageSize.Width - 0f) / chunk.GetWidthPoint());
        doc.Add(chunk);
        doc.Close();
    }
}