A script that places a company logo on an image?

This should work given that you properly reference the logo file:

//Loïc Aigon - www.ozalto.com
//Main routine
var main = function() {
//VARS
var doc, abs, nAb, n, rect, placed, layers, logosLayer, abH;
//The reference to the local logo file
const logoFile = File ( Folder.desktop+"/logo.pdf" );
if ( !app.documents.length ) {
alert("This scripts needs an open document !");
return;
}
//Checking file before placement
if ( !logoFile.exists ) {
alert("The logo file couldn't be found at\r"+logoFile.fsName);
return;
}
doc = app.activeDocument;
//Creating a new "logos" layer 
layers = getLayers(doc);
logosLayer = layers["logos"];
if ( logosLayer ) logosLayer.remove();
logosLayer = doc.layers.add();
logosLayer.name = "logos";
//Looping through artboards to add logo
abs = doc.artboards;
n = abs.length;
while ( n--) {
//processing nth artboard
nAb = abs;
rect = nAb.artboardRect;
abH = Math.abs ( rect[3]-rect[1] );
//Placing the file only once at first loop then duplicate instance after
if ( !placed ) {
placed = doc.placedItems.add();
placed.file = logoFile;
}
else {
placed = placed.duplicate();
}
//Setting logo properties
placed.layer = logosLayer;
placed.left = rect[0];
placed.top = rect[1]-abH+placed.height;
}
logosLayer.locked = true;
}
//Getting data on layers
function getLayers( doc ) {
var ls = doc.layers, n = ls.length, l, o = {}
while ( n-- ) {
l = ls;
o[l.name] = l;
}
return o;
}
//Running routine
main();

HTH

Ozalto | Productivity Oriented - Loïc Aigon