[@robin-w Moderator 5 years, 11 months ago]

if within content you can use

How to filter bbpress content in WordPress

but if at the bottom of ‘bbpress’ pages, then there are a bunch of actin hooks you can link to

do_action( 'bbp_template_after_forums_index' );
do_action( 'bbp_template_after_topics_loop' );
do_action( 'bbp_template_after_replies_loop' );
do_action( 'bbp_template_after_user_profile' );
do_action( 'bbp_template_after_search_results_loop' );

should get you most of the way there