Edit in JSFiddle

 function go() {
  var map = new ol.Map({
    target: "map",
    layers: [
      new ol.layer.Tile({
        source: new ol.source.GeoportalWMTS({
          layer: "ORTHOIMAGERY.ORTHOPHOTOS"
        })
      })
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([2.294, 48.858]),
      zoom: 15
    })
  });

  // Ajout de couche WMS
  var layerKML = new ol.layer.Vector({
    source: new ol.source.Vector({
      url: "https://geoservices.ign.fr/documentation/exemples/ressources/velib.kml",
      format: new ol.format.KML({
          // applique les styles du fichier KML
          extractStyles: true
        })
    })
  });
  map.addLayer(layerKML);

  // Ajout du contrôleur de couches
  var lsControl = new ol.control.LayerSwitcher({
    layers: [{
      layer: layerKML, // la couche KML
      config: {
        title: "Stations Vélib",
        // description: 'Cette couche représente le WMS'
      }
    }]
  });
  map.addControl(lsControl);

  // Gestion du clic sur la couche
  var gfiControl = new ol.control.GetFeatureInfo({
    options: {
        hidden : true,
        auto : true
    }
  });
  map.addControl(gfiControl);

}

Gp.Services.getConfig({
  apiKey: "jhyvi0fgmnuxvfv0zjzorvdn",
  onSuccess: go
});


#map {
  width: 100%;
  height: 400px;
}
<div id="map"></div>

External resources loaded into this fiddle: