System.Windows.Forms.SendKeys.Send("^+{ENTER}");

https://msdn.microsoft.com/en-us/library/aa382952(VS.85).aspx

https://social.msdn.microsoft.com/Forums/vstudio/en-US/76fff61c-a224-40bc-a108-2d3f2f616cd7/microsoft-terminal-services-library-programmatically-execute-a-batch-file-program-on-a-remote?forum=csharpgeneral

https://social.technet.microsoft.com/Forums/windowsserver/en-US/2a6c79cc-3890-4899-850c-a938320a4b6e/remoteapp-and-mstsclib?forum=winserverTS

https://social.technet.microsoft.com/Forums/windowsserver/en-US/1b3f1f70-9eea-45d8-a6c4-5c5a71e6fa1a/launch-ts-remote-app-from-terminal-services-api?forum=winserverTS

...
this.rdp = new AxMSTSCLib.AxMsRdpClient9NotSafeForScripting();
...
this.rdp.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("rdp.OcxState")));
...
private AxMSTSCLib.AxMsRdpClient9NotSafeForScripting rdp;
...
...
            rdp.Name = "RDP";
            rdp.Enabled = true;
            rdp.AdvancedSettings.allowBackgroundInput = 1;
            rdp.AdvancedSettings2.DisplayConnectionBar = true;
            rdp.AdvancedSettings2.SmartSizing = true;
            rdp.AdvancedSettings2.RDPPort = 3389;
            rdp.TransportSettings.GatewayUsageMethod = 2;
            rdp.TransportSettings.GatewayCredsSource = 0;
            rdp.TransportSettings.GatewayProfileUsageMethod = 1;
            rdp.TransportSettings.GatewayHostname = gateway;
            rdp.TransportSettings2.GatewayUsername = username;
            rdp.TransportSettings2.GatewayPassword = password;
            rdp.DesktopHeight = 768;
            rdp.DesktopWidth = 1366;
            rdp.Server = server;
            rdp.UserName = username;
            MSTSCLib.IMsTscNonScriptable secured = (MSTSCLib.IMsTscNonScriptable)rdp.GetOcx();
            secured.ClearTextPassword = password;
            rdp.ConnectingText = "Connecting...";
            rdp.DisconnectedText = "Disconnected";
            var ocx = (MSTSCLib.IMsRdpClientNonScriptable5)rdp.GetOcx();

            ocx.EnableCredSspSupport = true;
            ocx.AllowCredentialSaving = false;
            ocx.PromptForCredentials = false;
            ocx.PromptForCredsOnClient = false;
            ocx.WarnAboutSendingCredentials = false;
            ocx.AllowPromptingForCredentials = false;
            ocx.MarkRdpSettingsSecure = true;

            //rdp.AdvancedSettings7.DisableRdpdr = 0;
            //rdp.CreateVirtualChannels("CH001,CH002");

            var settings = (MSTSCLib.IMsRdpClientAdvancedSettings8)rdp.AdvancedSettings;
            settings.allowBackgroundInput = 1;
            settings.ClientProtocolSpec = MSTSCLib.ClientSpec.FullMode;
            settings.ConnectToServerConsole = true;
            settings.EnableCredSspSupport = true;
            settings.EncryptionEnabled = 1;

            rdp.Connect();
...