But, this Lightroom Tutorial will show you that you have more options in the Lightroom Print Module! Now, it is not going to happen in a batch export, but if you want to customize your logo on separate photos, read on for a quick tutorial.
When you have your photos in your filmstrip, just click over to the Print Module. The Print Module allows for a logo upload through the Identity Plate in the left column, under Page. You can type in the identity plate or upload a .png logo. You may then place the logo WHEREVER you want! Yes! And, you can also size it and lower the opacity.
Here are a few samples. Below is an example of a full screen logo over the image with low opacity.