As mentioned in tbe above post, there is support for it and not knowing how other language versions function in terms of defaults but in the English copy of Acrobat these settings are not set up as defaults and with the link provided it will get you going. However, from my understanding, there a very few Arabic fonts that are set up for PDF's sepcfically. However, there is only one font that does this for both Acrobat and Reader and that is ArabicTypesetting, check your font folder to see if it is installed on your machine. It goes by the name of Arabic Typesetting Regular, I believe that is the font you want to use in PDF's.