The calling code is fundamentally a call to the function bcn_display(). There may be some extra code surrounding it for presentation purposes (keeping things from being called if the plugin isn't activated, etc.), but . Examples of the two standard calling code blocks are available within the "Quick Start" section of the built in help (click the help tab in the Breadcrumb NavXT settings page within your WordPress admin area).
The calling code does not have to be in "the loop", it was designed to work outside of "the loop" (and probably works inside the loop) to increase flexibility.
For the linked site I'm seeing:
<div class="breadcrumb">
<?php
if(function_exists('bcn_display'))
{
bcn_display();
}
?>
</div>
<?php } ?>
the area between the<?php and ?>is the code that PHP is supposed to be reading and executing, it shouldn't show up in the output HTML that a browser sees. I noticed a stray<?php if ( !is_front_page() ) { ?>
that is being output as well. Something is very goofy here.
I guess the first thing to look at is where did you place the calling code? In particular, what is the name of the file it is located in?
Or, by chance, did you try placing it in a text widget or something along the lines of a PHP code execution widget? I could see that causing this issue. If you want to use a widget, a Breadcrumb NavXT widget is provided as part of the normal plugin install.