Include a file in post and pages

I use this in some of my templates directly in the file.
But now i am in need of some plugin to be able to do this directly in the post and pages.

This is the code, <?php include('somefile.php');?> now what plugin do i need to be able to include that? I have tried two different php in post and pages plugins but they did not manage to get it done.

It must be possible since when using it directly in the template file of a page it includes the file and display its content.

Thanks.