I removed the <?PHP and ?> tags and I included the full URL which is: http://www.jsdstudios.nl/website/JSD%20Studios/silverstripe/php.ini in the .htaccess file. I still keep the error so I think I just ignore the error...Tnx for all the help!
yea it's not the URL, its the actual path on the server, so it will still be wrong. Are you using Cpanel as your host control or does you host have a propriatory system? On Cpanel if you go to the file manager, it's the path that is in brackets at the top of the file tree and will look something like the examples I gave above.
Anyway if it works for now then it should be fine :)