Conditional redirect on login using referring URL

just use the login_redirect filter and return RSVP form page permalink.

add_filter( "login_redirect", "redirect_on_login", 10, 3 );
function redirect_on_login( $redirect_to, $requested_redirect_to, $user ) {
    // check the user's role
    $role = $role = array_shift($user->roles);
    if( $role == "custom-role" ) {
        return get_permalink(/* post/page id of RSVP Form */);
    }
}