<image>As shown in the figure, the side length of the square $$AOCB$$ is $$4$$. The graph of the inverse proportional function $$y= \dfrac{k}{x}$$ ($$k\neq0$$, and $$k$$ is a constant) passes through point $$E$$, and $$S_{\triangle AOE} = 3S_{\triangle OBE}$$.
$$(1)$$ Find the value of $$k$$.
$$(2)$$ The graph of the inverse proportional function intersects line segment $$BC$$ at point $$D$$. The line $$y= \dfrac{1}{2}x+b$$ passes through point $$D$$ and intersects line segment $$AB$$ at point $$F$$. Extend $$OF$$ to intersect the inverse proportional function $$y= \dfrac{k}{x}(x < 0)$$ at point $$N$$. Find the coordinates of point $$N$$.