It may have some difference in value, but not a significant amount of money. It may add value in that a buyer looking for privacy lot might choose your hone over one with less land. For some buyers looking in your area, they may not want the extra costs associated with maintaining a larger lot. One the plus side, your probably not paying a large amount of property taxes for the land.

assuming the lot is not further subdividable, many times you have a home on a large lot because a good portion of the lot is wet or a steep hill or drop off and not good for anything else. So, if it is not usable it has no real value other than privacy. If it is usable it does add value, at a percentage. in other words example:
1 acre is $100,000, 2 acres is $110,000, its not double, or something like this.

Why would the lot size increase the value of the home particularly when it is unique to the area. The appraiser likely has no comps to compare the property too and support additional value in the lot size. Is it big enough to be sub divided?