Update saving_charts.rst
@@ -49,7 +49,9 @@ Firefox, which requires the following:
installation.
Once those dependencies are installed, you should be able to save charts as
-``png`` or ``svg``.
+``png`` or ``svg``. Altair defaults to using chromedriver. If you'd like to use geckodriver::
+
+ chart.save('chart.png', webdriver='firefox')
Figure Size/Resolution
^^^^^^^^^^^^^^^^^^^^^^
