Under the terms of the rights issue, investors can buy seven new shares for every nine shares they own at 22.55 pounds each, a discount of 32.2% to the theoretical ex-rights price.
Shares in the company fell 2.1% to 4,118 pence in early trade.
Aveva's $5 billion purchase will help expand its services with the California-based firm's PI system, which makes software that captures data from ships, chemical boilers, power plants and other facilities in industries including oil and gas, mining, pulp and paper and water.
The British company, which had planned the rights issue in August to help fund the deal, said it will offer 125.7 million shares in the rights issue.
France's Schneider Electric, which indirectly holds a 60% stake in the company, has undertaken to take up its rights in full on a pro rata basis, Aveva said.
It is also funding the deal with cash on its balance sheet, new debt and by issuing shares to one of OSIsoft's shareholders, Estudillo.
(Reporting by Tanishaa Nadkar in Bengaluru; Editing by Shailesh Kuber)