Button/Javascript to attach MULTIPLE files

I am using the following code that attaches only one file to a PDF.  How could I change my code to allow to attach multiple files?

try {

    var annot = this.addAnnot({

        page: 0,

        type: "FileAttachment",

        point: [500, 500],

        noView: true,

        author: "Attachment"

    });

    annot.cAttachmentPath;

    var attachmentObj = annot.attachment;

    if (attachmentObj !== null) {

        app.alert("Add this file: " + attachmentObj.name);

        var l = this.getField("lst1");

        l.insertItemAt(attachmentObj.name, 0);

    }

}

catch(e) {

    if (e.name == "NotAllowedError") {

        // do nothing

    }

}