There is no definition for authorization for each document. If your management is ready to give you authorization to sign the document, then you can sign on appointment letters, offer letters, PF digital signature,etc.
When new joinee join the company, you need to issue him appointment letter, company policies (Leave policy, attendance policy etc).
Feel free to call or revert for any assistance.
21st March 2018 From India, Bangalore
22nd March 2018 From India, Mumbai
In absence as suggested by Mr KK you need to adopt a policy document on 'Delegation of Powers'.
23rd March 2018 From India, Mumbai