此扩展被认为已无人维护及已消亡。然而，此扩展的源代码还可在 PECL SVN 找到： » https://svn.php.net/viewvc/pecl/fdf.
This extension is no longer bundled with PHP.
注意: If you run into problems configuring PHP with fdftk support, check whether the header file fdftk.h and the library libfdftk.so are at the right place. The configure script supports both the directory structure of the FDF SDK distribution and the usual DIR/include / DIR/lib layout, so you can point it either directly to the unpacked distribution directory or put the header file and the appropriate library for your platform into e.g. /usr/local/include and /usr/local/lib and configure with --with-fdftk=/usr/local.
注意: Note to Win32 Users
为了使此扩展生效， DLL 文件必须能在 Windows 系统的 PATH 指示的路径下找到。如何操作的信息，请参见题为“如何在 Windows 中将 PHP 目录加到 PATH 中”的FAQ。虽然将 DLL 文件从 PHP 文件夹复制到 Windows 系统目录也行，但不建议这样做。 此扩展需要下列文件在 PATH 路径中： fdftk.dll