Its very easy to show custom taxonomies as select options list in the options panel of redux framework.
I used following paremeter to get list of custom taxonomies:
'fields' => array( array( 'id' => 'slider_type', 'type' => 'select', 'title' => __( 'Select Slider for Homepage', 'redux-framework-demo' ), 'subtitle' => __( '' ), 'desc' => __( 'Above you will select the slider from the list of slider types which you created.', 'redux-framework-demo.', 'redux-framework-demo' ), 'data' => 'terms', 'args' => array('taxonomies'=>'slidertype', 'args'=>array('hide_empty'=>0)), ), )