GetInstance

public static RedactorConfiguration GetInstance()

var adobePhotoshopSettings = new DocumentFormatConfiguration();
adobePhotoshopSettings.ExtensionFilter = ".psd";
adobePhotoshopSettings.DocumentType = typeof(MyAdobePhotoshopFormatInstance);
var configuration = RedactorConfiguration.GetInstance();
configuration.AvailableFormats.Add(adobePhotoshopSettings);