You could check out the signatures plugin, since it does basically that, and a lot more:
https://github.com/NoahY/q2a-signatures
Here is the example from that plugin:
function q_view_content($q_view)
{
$this->signatures = array();
if (qa_opt('signatures_enable') && qa_opt('signatures_q_enable')) {
$result = qa_db_read_all_assoc(
qa_db_query_sub(
'SELECT signature,userid,format FROM ^usersignatures'
)
);
foreach($result as $user) {
if ($user['signature']) {
$informat=$user['format'];
$viewer=qa_load_viewer($user['signature'], $informat);
global $options;
$signature=$viewer->get_html($user['signature'], $informat, array(
'blockwordspreg' => @$options['blockwordspreg'],
'showurllinks' => @$options['showurllinks'],
'linksnewwindow' => @$options['linksnewwindow'],
));
$this->signatures['user'.$user['userid']] = $signature;
}
}
if(@$this->signatures['user'.$q_view['raw']['userid']]) {
if(!isset($q_view['content'])) $q_view['content'] = '';
$q_view['content'].=qa_opt('signatures_header').$this->signatures['user'.$q_view['raw']['userid']].qa_opt('signatures_footer');
}
}
qa_html_theme_base::q_view_content($q_view);
}
This is doing more than you need, it's populating an array of signatures to be used in the answers and comments as well, but it does add to $q_view['content'], which is what I assume you are looking for.