Part of the instructions for integrating Dokuwiki and SMF say:
$conf['pathtosmf'] ='/home/user/public/pathtosmf'; //path to your smf api without trailing slash, /home/user/public/pathtosmf
4. Make sure you have uploaded the correct smf_api.php to your forum root, the path to the api file above.
Where the hell do I put smf_api? I can't find the directory '/home/user/public/pathtosmf'?
umm... "pathtosmf" obviously has to be replaced by your smf installation path. common sense, dude :P