Xinia,
It may well be that you will never find a record of the birth/baptism of Robert - but I wish you luck.
However, you might be able to find the names of the parents of his mother.
I would not assume that Ann's father's given name was Thomas from the given names of Thomas Finnie SUTHERLAND - the mother's maiden surname could quite often be used as a middle name for a later child who did not bear the first name of his (or her) maternal grandparent.
It seems that you need to check out later censuses to find when the parents - Robert SUTHERLAND & Anne (FINNIE?) SUTHERLAND might have died.
And then check out their deaths on the (pay per view - charges are reasonable) ScotlandsPeople site at:
http://scotlandspeople.gov.ukScottish death certificates are very informative and give (if the informant knew them) the name and occupation of the father of the deceased, and the name and maiden surname of the mother of the deceased.
However, a free search on SP finds just one death in the Statutory Registers for an Ann* SUTHERLAND, other name FINN*. Progressively refining the parameters finds Ann SUTHERLAND, other name FINNIE, year of death 1887, age 56, place Dunfermline.
It seems as though it would be worth downloading this certificate.JAP