It might be a bit jarring to see Sony Open in Hawaii contender Si Woo Kim being lined up by his caddie ahead of almost every shot. That's not something typically seen on the PGA Tour, and it's a practice that's slowly disappearing on the LPGA Tour.
The Rules of Golf allow a player to be lined up by their caddie -- or anyone else -- ahead of any shot. However, the caddie is prohibited from standing directly behind the player's intended swing path as they execute the shot. If the caddie doesn't move before the player swings the club, then the player is assessed a two-stroke penalty (or loss of hole in match play).
Look at Rule 8-2 (a):
Except on the putting green, a player may have the line of play indicated by anyone, but no one may be positioned by the player on or close to the line or an extension of the line beyond the hole while the stroke is being made. Any mark placed by the player or with his knowledge to indicate the line must be removed before the stroke is played.
On the putting green, a player's caddie (or partner in a team competition) can help line up putts and point out the intended line but cannot touch the putting surface.
