Forces and equilibrium — practice question

A smooth ring $R$ of mass $0.2\,\text{kg}$ is placed on a light string $ARB$. The two ends of the string are fixed at points $A$ and $B$, with $A$ vertically above $B$. The string is taut, and $ABR = 90^\circ$. The angle between the segment $AR$ of the string and the vertical is $60^\circ$. The ring is kept in equilibrium by a force of magnitude $X\,\text{N}$, acting on the ring in a direction perpendicular to $AR$ (see diagram).