series.markers.size Number|Function (default: 6)

The marker size in pixels.

Example - set the chart markers size

<div id="chart"></div>
<script>
$("#chart").kendoChart({
  series: [{
    type: "line",
    markers: {
      visible: true,
      size: 30
    },
    data: [1, 2, 3]
  }]
});
</script>