Racking my brain
Try so hard to remember or think of something

Rain cats and dogs 
Rain very hard

Raise a stink
Protest in an aggresive way

Rat race
Dirty and unfair competition

Raw deal
Unfair deal

Read between the lines
Try to understand the true meaning inside

Read someone's mind
Try to understand someone's thought

Real deal
Very good, Very satisfied.

Red carpet
Very important, very special.

Renaissance man
A very smart and talented person

Ride high
Very successful

Ride with the tide
Follow the others agreement

Road hog
A bad driver

Rob Peter to pay Paul
Borrow money from someone to pay another.

Rock the boat
Sway the situation. Break the stable stage.

Roll the dice
Take a risk on something.

Roll with the punches
Flexible

Rolling stone
Person who never stay in any place/ position for long.

Root and branch
Through /All over.

Rough and ready
Simple

Rough diamond
Person who doesn't look nice from the outside but is actual a good / nice one.

Run against someone
Compete with someone

Run behind
Delay / slower than schedule

Run out of
All gone. No more left.