Form 709, Schedule A, Part 1, line 1, column D (Donor’s adjusted basis of gift) and column F (Value at date of gift).

I inherited a property from my father in 2003.  The property was appraised at $121,500 at that time for my basis.  I have used this property for as a second home and for personal use since that time.  I sold this property to my son in 2022 for $115,000, $6500 less than my basis.  I received a 1099-S reporting the gross proceeds of $115,000 in box 2.  No depreciation ever taken and not claiming any loss.  The 2022 current appraisal is $230,000.  I believe that I need to report the $99,000 gift of equity on IRS Form 709 (i.e. $115,000 - $16000 annual gift allowance = $99,000)

My question pertains to Form 709, Schedule A, Part 1, line 1, column D (Donor’s adjusted basis of gift) and column F (Value at date of gift).  I’m just not certain and a bit unclear about the correct values for these two entries.  Any help, advice, and clarification will be appreciated.  Thank you.