Here's a link to a picture
. The pattern is just establishing which is the WS for future reference later in the pattern (the odd rows will be WS).
If you work rows 1-7 and then work even for another 7, you'll end with row 14 which is a RS row. Since the directions want the next row to be a RS row, a purl row for the decreases, you could add in an extra row so that you end with the WS and you're ready to put the decreases in on the purl row which is a RS row. Yes, decrease across this purl row.
Since it looks like the rest is stockinette, you could go ahead as you have it now and put the decreases in on the next row if you want or just take out the last row and put them in on the purl row as the directions say. Take a look at the back and make sure this will match up with the back. If you can't tell the difference, no one else will be able to either!