$subscription_id = "<Subscription_ID>"
$NetworkName = "<Network_Name>"
$location = "<Region>"
$netrgname = "<Resource_Group_VNet_is_in>"
$AppServiceName = "<AppService_Name>"
 $props = @{
      "vnetResourceId" = "/subscriptions/$subscription_id/resourcegroups/$netrgname/providers/Microsoft.ClassicNetwork/virtualNetworks/$NetworkName";
      "certThumbprint"= "<Client_cert_thumbprint>";
      "certBlob"= "<Base64_Cert_Data>";
      "routes" = $null;
      }

New-AzureRMResource -ResourceName "$AppServiceName/$AppServiceName-to-$NetworkName" -Location $location  -ResourceGroupName MarcusWebsites -ResourceType Microsoft.Web/sites/virtualNetworkConnections -PropertyObject $props -ApiVersion "2015-08-01" -force