"rather poorly" is correct and can be used in written English.
Example: The student performed rather poorly on the exam, despite studying diligently.
Adult stem cells, by contrast, proliferate rather poorly in culture.
Of course, most of these stories ended rather poorly.
But some larger emerging markets fared rather poorly.
Compared with staff at other English Russell Group universities, Oxbridge academics are paid rather poorly.
(A book on Grinberg, with many useful though rather poorly reproduced illustrations, was published by Carré Noir in 1996).
Could the endless publicity Bolt has lavished on his tome be because it is selling rather poorly in the bookshops?
And so, despite stellar results for the first three quarters of this year, advertising shares have performed rather poorly.
The conference was bedevilled by a certain amount of mutual incomprehension, because some of the reporters speak English rather poorly.
"The book, or pamphlet, is rather poorly written," a columnist wrote in the British newspaper The Independent.
Actually, the dish's main shortcoming is that it comes off rather poorly when compared with the other mains.
"I remember doing rather poorly as it seemed that there was a delay from when I yelled 'Pixxx' to the actual firing of the gun," Mr. Anderson said.
