add a new column (which you can remove later) that will pre-pend the text "Rycote" to the contents of an existing cell.
Let's say the exisitng data is in column C and you add a new column D like:
now select D1, and grab (click and hold) the little circle at the bottom-right corner of the selected cell, then drag down as needed to fill. Another way to do this (and this is the way you will want to do this is to select D2, copy, then scroll all the way to the end of the column, then shift click the last cell in the column. This will select ALL the cells in that column, paste to fill them all with the same formula.
The last step is to select column D, then copy, then select column C, then use the menu item "Edit > Paste Values", now remove column D