  Motivated by recent progress in 2D spintronics, we present Eu deposited on a
1H-WSe$_2$ as a promising platform for engineering spin-orbit effects and Berry
curvature. By first-principles calculations based on density functional theory,
we show that Eu/WSe$_2$ exhibits intriguing properties such as high magnetic
anisotropy, valley-dependent polarization of spin and orbital angular momenta,
and their Rashba textures. These originate from magnetic and spin-orbit
proximity effects at the interface and the interplay between localized $4f$
magnetic moments of Eu and mobile charge carriers of WSe$_2$. We find a
pronounced anomalous Hall effect in the proposed system. Thus, we promote $4f$
rare-earth metals deposited on top of a transition-metal dichalcogenides as a
promising platform for 2D spintronics.
