Search a range for value and if true put a x in a cell

I have a problem and I don't know how to make it work

I have a column of peoples names and I would like to search that column for a specific value and if that value is in that column then place an 'x' in the cell.

It is for a rota so if that persons name appears in the column for the date in question, then put an 'x' in the day that corresponds to that date

I have included the worksheet so you can see what i am trying to do.

I did think i could use an if statement to make a comparison but it won't let me choose a range

To check whether Adam is in the list, and return an "x" if he is

=IF(ISNUMBER(MATCH(D6,$A1:$A10,0)),"x","")