Using MultiPostThumbnails Plugin, trouble adding an IMG Attribute for .js use

In the portfolio theme I’m creating, I’m utilizing a plugin (Multiple Post Thumbnails) to add a second feature image to the top of my portfolio posts. I would like to add this script adaptive-backgrounds.js to allow the background (when visible) to change color based on a sample from that second feature image I’m including in a div with an id of “folio-image”. Here’s a post from the theme in progress: sample post

The problem
The script requires an img attribute of data-adaptive-background=’1′
I can’t seem to include the attribute onto the image. I realize that the_post_thumbnail(); accepts two parameters one of which is an array for adding in attributes. Apparently though, I am doing it wrong. I’m still learning so not sure of the correct syntax for everything. Currently I have the Mutliple Post Thumbnail plugin activated and the following code is placed in my functions.php file:

if (class_exists('MultiPostThumbnails')) {
    new MultiPostThumbnails(
        array(
            'label' => 'Portfolio Image',
            'id' => 'folio-image',
            'post_type' => 'post'
        )
    );
}

On my single.php file I’ve included:

<div id="folio-image">
<?php if (class_exists('MultiPostThumbnails')) :
    MultiPostThumbnails::the_post_thumbnail(
        get_post_type(),
        'folio-image'
	);
endif; ?>
</div>

The image displays as needed. But I’m not sure how to include the needed attribute. This link on Stackoverflow says to include it like so: the_post_thumbnail( 'folio-image', array( 'data-adaptive-background' => 1 ) ); I can’t seem to figure out where to place that having tried multiple times.

I feel like the answer seems to be in the plugin documentation here. Where it says to use the wp_get_attachment_image() argument for adding attributes. But after trying several approaches and getting not much more than a few parse errors and/or no change to the image at all, I haven’t been successful in including the needed atttribute.

Thanks in advance for any help you might have. I always appreciate the WP community’s willingness to help.