A ball can safely consume food items that are 15-20% of it's body weight. So 206 gram rat should be fine - those are about the same size as what I feed my adult balls give or take. Aside from whether or not there is an issue with her getting it down and keeping it down she needs to be able to digest it before it starts to rot in her belly - ideally you shouldn't see a lump after 24-36 hours. Make sure she has some good belly heat to help her digest and she should be fine.
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Tosha 
"Nihil facimus sed id bene facimus"
7.33.0 Ball Python (Harry and Fluffy and gang)
1.0.0 Angolan Python (Anakin Skywalker)
0.0.1 Green Tree Python (Verdi - yeah I know but my kids love the book)
0.2.0 Feline (Pippen and Pandora)
0.0.1 Desert Tortoise (Pope John Paul aka JP )
2.2.1 Fish (1,2,3,4)
0.0.2 frogs rescued from pool skimmer