Atworthy probably has searched all the likely BMD on ScotlandsPeople and drawn a blank.
The passenger list for the 'Tasman' has James Anderson aged 25 years as a single man from Kintail, Perthshire (a long distance apart). Was he born in Kintail and moved to Perthshire in search of work? Catharine Robertson aged 27, single woman and domestic servant from Perthshire, so she probably was in service and away from home.
Not many others from Perthshire - the ship left from Plymouth?
Other passengers worth noting who may be related:
a) Peter Robinson aged 22 years and single man from Redurdin, Perthshire. Almost certain to be a Robertson from Redgorton in Perthshire. 1841 census for Redgorton (3/5) has a 15 year old Peter Robertson which would fit. No other Robertsons at (3/5) so not with family. (The 1841 census probably will only say 'born in Perthshire', which won't be much help)
b) Donald Robinson aged 28 years. Married man with wife Jane (24y) and daughter Nancy (1y) from Blairgowrie, Perthshire. This will be another Robertson family.
Susan Robertson should be in the 1841 census aged about 10 years which normally would be too young to be a domestic servant, unless for a close relative. There are only about a dozen in the 5 - 15 age range, and the best bet is Blairgowrie (5/17) where 10 year old Susan probably is living with father Donald but mother Betsy, not Ann, (and not even certain if Betsy is a Robertson), 2 sisters Christian and Elizabeth. Susan is absent in the 1851 census.
The ferrets cannot spend credits on non-clients, so these are only guesses.
Throth's ferrets