Yes. You do that with the preferences. You'll need to push these preferences to all users. You can use "Security Settings Export/Import" feature for that Export is available only in Acrobat, Import is available in both Acrobat and Reader. You can also use Customization Wizard to create a customized Acrobat/Reader installer that pushes these preferences. In IT-controlled environments you can also use GPO to push these preferences to all users.
Thanks for the quick info. But as of now if user enters the reason as none, acrobat does not validate, as we need to mandate the reason. we have a requirement where reason is mandatory user has to enter reason(Not "none').
What do you mean Acrobat does not validate? Do you mean it does not validate whether the reason is set or is "none"?
There is no preference that mandates that the user enters a reason other than "none" at signing.
If you prepare to-be-signed PDFs with unsigned signature fields which the users then sign, you do that with seed values. You associate with these signature fields seed values that specify an array of reasons (possibly different reasons for different signature fields) and mandate that one of them is selected during the signing.