write method: where to put font file?

[tarrasque73]

I'm trying to pick up an image in Twig and write a watermark text on it using the write function, like:

The cropResize works perfectly (and all other methods I've tested so far). The write method does not.

I tried putting the Arial.ttf file in a lot of places in the deployed file structure, but still does not work. Where should font files go?

Thanks