Nevermind, I found the settings in the plugin config.php
define(‘WP_RP_THUMBNAILS_WIDTH’, 150);
define(‘WP_RP_THUMBNAILS_HEIGHT’, 150);
define(‘WP_RP_CUSTOM_THUMBNAILS_WIDTH’, 150);
define(‘WP_RP_CUSTOM_THUMBNAILS_HEIGHT’, 150);
I reduced these all to 120 (my images all had a height of 125) and it worked.