The phrase "a rather more difficult" is correct and usable in written English.
It can be used when comparing the difficulty of two or more things, often to emphasize that one is significantly more challenging than another.
Example: "This problem is a rather more difficult challenge than the previous one we encountered."
Alternatives: "somewhat more difficult" or "considerably more difficult".
The psychological wounds of my mother's death haven't yet been healed and we are now faced with a rather more difficult circumstance that adds further to our woes.
But as New Scientist reports, another team from Oxford's Department of Engineering Science, which has been working with Google DeepMind, has bitten off a rather more difficult task.
"But if I look at employment, it's a rather more difficult story, because obviously a company as successful as ARM only employs about 1,000 people in this country".
But its peculiar dramatic alchemy — the way Nemes places his mad formal audacity in service of a tangled, perversely withholding narrative — makes it a rather more difficult one to absorb.
And when he sings, what comes out sounds strained and parched, drained of its usual power, but with a different, rather more difficult kind of potency in its place.
A quick roadside fix a rubber band to keep the throttle open just wide enough to potter along allowed him to limp home by judiciously slipping the clutch and applying the brakes.Stopping a runaway car is rather more difficult nowadays.
In August 2010 a J&J subsidiary recalled artificial hips, rather more difficult to remove than a pill bottle from a cabinet.
On the other hand, a defeat – or even a draw – would make things rather more difficult.
The big mystery of course in the housing price puzzle is interest rates – a puzzle that has become rather more difficult to unravel with the election of Donald Trump.
Growing and selling marijuana the proper way is rather more difficult than simply popping a plant under a black light in your closet.
