<div id="pdfviewer"></div>
<script type="module">
$("#pdfviewer").kendoPDFViewer({
    toolbar: {
        items: [
            {
                type: "button",
                text: "Custom",
                attributes: {
                    "data-action": "custom",
                    "title": "Custom Action"
                }
            },
            "pager"
        ]
    },
    pdfjsProcessing: {
        file: {
            url: "https://demos.telerik.com/kendo-ui/content/web/pdfViewer/sample.pdf"
        }
    }
});
</script>