Batch Stamping of PDFs

In need of a little help. Need a short javascript code chunk to past a custom stamp on the first page of each selected PDF. Want the Stamp to appear in the upper-left hand corner of the page. I have been working with the sample code. For some reason I been unable to change the stamp being applied in the following code:

/* Insert Stamp */

// Get the crop box of the first page

var aCrop = this.getPageBox()

var semiWidth = aCrop[2]/2;

var semiHeight = aCrop[1]/2;

// Get the center of the crop box.

var x = semiWidth;

var y = semiHeight;

// Make the width of the stamp roughly .67% of the cropped page width, and

// make the height of the stamp 25% of the stamp's width

semiWidth = 0.67*semiWidth;

// Make width .67 of width of page

semiHeight = 0.25*semiWidth; // Make height .25 of semiWidth

var Rect = new Array (x-semiWidth,y-semiHeight,x+semiWidth,y+semiHeight);
// The matrix m transforms from rotated to default user space

var m = (new Matrix2D).fromRotated(this,0)

// Transform Rect from rotated to default user space

Rect = m.transform(Rect)

// Now add our annotation using the Rect array for the rect property

var annot = this.addAnnot

({

page: 0,

type: "Stamp",

name: "myStamp",

rect: Rect,

contents: "This document has been approved.",

AP: "Void"

});