var docPreset = new DocumentPreset;
docPreset.units = RulerUnits.Millimeters;
docPreset.width = 210 * 2.8346456;
docPreset.height = 297 * 2.8346456;
docPreset.colorMode = DocumentColorSpace.RGB;
var doc = app.documents.addDocument(DocumentColorSpace.RGB,docPreset);