//See the "Example" Project for a MigraDoc example
static void Main(string[] args)
{
    GlobalFontSettings.FontResolver = new FontResolver();
    
    var document = new PdfDocument();
    var page = document.AddPage();
    var gfx = XGraphics.FromPdfPage(page);
    var font = new XFont("OpenSans", 20, XFontStyle.Bold);
            
    gfx.DrawString("Hello World!", font, XBrushes.Black, new XRect(20, 20, page.Width, page.Height), XStringFormats.Center);

    document.Save("test.pdf");
}

//This implementation is obviously not very good --> Though it should be enough for everyone to implement their own.
public class FontResolver : IFontResolver
{
    public byte[] GetFont(string faceName)
    {
        using(var ms = new MemoryStream())
        {
            using(var fs = File.Open(faceName, FileMode.Open))
            {
                fs.CopyTo(ms);
                ms.Position = 0;
                return ms.ToArray();
                }
            }
        }
        public FontResolverInfo ResolveTypeface(string familyName, bool isBold, bool isItalic)
        {
            if (familyName.Equals("OpenSans", StringComparison.CurrentCultureIgnoreCase))
            {
                if (isBold && isItalic)
                {
                    return new FontResolverInfo("OpenSans-BoldItalic.ttf");
                }
                else if (isBold)
                {
                    return new FontResolverInfo("OpenSans-Bold.ttf");
                }
                else if (isItalic)
                {
                    return new FontResolverInfo("OpenSans-Italic.ttf");
                }
                else
                {
                    return new FontResolverInfo("OpenSans-Regular.ttf");
                }
            }
            return null;
        }
    }
}