The array does not have 110 rows -- it has only 34. Are you sure you're indexing by RF(row, columns, slice) and not by RF(x, y, slice)? Because y is row, it comes first, like RF(y, x, slice). Otherwise just read to the end with
RF6 = RF(60 : end, 5 : end, :);
but it will have to have at least 60 rows and 5 columns.