Functions are easy to call inside a select loop, but they don't let you run inserts, updates, deletes, etc. They are only useful for query operations. You need a stored procedure to manipulate the data.
So, the real answer to this question is that you must iterate through the results of a select statement via a "cursor" and call the procedure from within that loop. Here's an example:
DECLARE @myId int;
DECLARE @myName nvarchar(60);
DECLARE myCursor CURSOR FORWARD_ONLY FOR
SELECT Id, Name FROM SomeTable;
OPEN myCursor;
FETCH NEXT FROM myCursor INTO @myId, @myName;
WHILE @@FETCH_STATUS = 0 BEGIN
EXECUTE dbo.myCustomProcedure @myId, @myName;
FETCH NEXT FROM myCursor INTO @myId, @myName;
END;
CLOSE myCursor;
DEALLOCATE myCursor;
Note that @@FETCH_STATUS
is a standard variable which gets updated for you. The rest of the object names here are custom.