You can include xml file and can modify the xml file according to your requirement, you can find the xml file of the "H264 Adaptive Bitrate MP4 Set SD 16x9" encoding format here
var inputAsset = context.Assets.Where(a => a.Id == inputAssetId).FirstOrDefault();
if (inputAsset == null)
throw new ArgumentException("Could not find assetId: " + inputAssetId);
var encodingPreset = "H264 Adaptive Bitrate MP4 Set SD 16x9"; // <a href="http://msdn.microsoft.com/en-us/library/windowsazure/jj129582.aspx#H264Encoding">http://msdn.microsoft.com/en-us/library/windowsazure/jj129582.aspx#H264Encoding</a>
var encodingPresetConfig = File.ReadAllText(@"D:\WAMS\DynamicPackagingUpload\DynamicPackagingUpload\DynamicPackagingUpload\Encoding.xml");
IJob job = context.Jobs.Create("Encoding " + inputAsset.Name + " to " + encodingPreset);
IMediaProcessor latestWameMediaProcessor = (from p in context.MediaProcessors where p.Name == "Windows Azure Media Encoder" select p).ToList()
.OrderBy(wame => new Version(wame.Version)).LastOrDefault();
ITask encodeTask = job.Tasks.AddNew("Encoding", latestWameMediaProcessor, encodingPresetConfig, TaskOptions.None);
encodeTask.InputAssets.Add(inputAsset);
encodeTask.OutputAssets.AddNew(inputAsset.Name + " as " + encodingPreset, AssetCreationOptions.None);