MAC OSX Newgrf dir

[TGVfan]

Last time I installed OpenTTD, it was on a windows machine and I had to make a Newgrf folder/dir for additional graphics.
I recently installed OpenTTD on a Mac and I whilst browsing through the downloadable content I noticed a lot is still not included (like Dutch trainset, stations and OHLE)
So.... where does OTTD (on a Mac) installs the new graphics? And how can I install them?

Thanks

[planetmaker]

It installs them exactly there where the readme in section 4.2 tells you it installs things.

If you use the ingame content download you don't have to worry about the place where things get installed. Otherwise look at ~/Documents/OpenTTD and subdirs.