I have been trying to figure out how to get credit for the retweets option. The Marriott Plus Points site indicates you get credit for: "Retweeting our posts to your Twitter feed each day and tagging it with the #MRpoints hashtag"

How does one tag the retweet with the #MRpoints hashtag? When I hit retweet to a twitter sent by one of the Marriott properties I am following, I don't have any option to add any additional hashtags. How would one do this and get credit for it using the web version of Twitter?