// step 2
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("layers.pdf"));
writer.setPdfVersion(PdfWriter.VERSION_1_5);
writer.setViewerPreferences(PdfWriter.PageModeUseOC);
// step 3
document.open();
// step 4
PdfContentByte cb = writer.getDirectContent();
LwgPhrase explanation = new LwgPhrase("Layer radio group and zoom", new LwgFont(LwgFont.HELVETICA, 20, LwgFont.BOLD, Color.red));
ColumnText.showTextAligned(cb, LwgElement.ALIGN_LEFT, explanation, 50, 650, 0);
PdfLayer title = PdfLayer.createTitle("Layer radio group", writer);