I.R.I.S. Readiris 14 for Windows User Guide - Manual (Page 122)

Readiris TM 14 – User Guide
129
To password-protect PDF documents:

Click the Format button in the Output group.

Select the required PDF type from the drop-down list.

Then click the Password tab.

When you set an open document password, you will be
prompted to enter that password when opening the PDF output.

When you set a permissions password, you will only be able to
perform the actions specified in the security settings. If you do
want to change these settings, you must enter the permissions
password.
The Readiris security settings are similar to the standard protection
features offered by Adobe Acrobat.