Assalamu Alaykum,
Allamah Quhustani’s “Jami’ ar-Rumuz” could be downloaded from here:
http://www.mediafire.com/?zzhzdmmmymd
This is an extremly rare edition, printed 150 years ago in Calcutta. A more common edition, is the Qazan edition, available from H.M.Saeed of Karachi.
The book does contain some weak views, which sadly have crept into the works of those after him, like the Hashiyah of Ibn Abidin, inspite of Allamah Ibn Abidin himself declaring the book unreliable! eg. the kissing of the thumbnails during adhan, the dua between every 4 rak’at of tarawih etc
[Mufti] Husain [Kadodia]
at-Tahawi 
Assalaam wa ‘alaikum,]
why does the presence of weak views make the book unreliable?! Things don’t just creep in to the books of master like ibn ‘Abidin and so forth, there must be a more profound explaination for their presence .
wassalaam
Tanveer
If you read the introduction of Radd Al-Muhtar Ibn Abidin mentions that he quotes from these books intentionally in order to mention the weak opinion, not that he always supports that view. That’s why usually he says after mentioning a weak view “fa-l-yutammal” or “yuharrar” etc.