Form 1099r..california box 14 blank, fed tax amount box 2a filled. state return when asks about ira distributions adjustments, do you enter the difference as subtraction?

No, 1099-R Box 14 is typically blank.

This is if you have a different taxable amount of distribution for Calif than for federal. For instance the IRA contribution deduction amount in 1982 - 1986 was different between Calif and federal so you may have a Calif "cost" (contributions not deducted) to recover before it begins to be taxable. If that is your situation then the Calif taxable amount could be less than the federal amount.

If you don't already *know* that your state taxable amount should be different, then it's not. It's just asking if you have any adjustments - that doesn't mean you should.

Calif has a publication 1005 - Pension and Annuity Guidelines, here http://www.ftb.ca.gov/forms/2018/18_1005.pdf
that describes this in more detail.