  We theoretically study noncoplanar spin textures in polar magnetic
conductors. Starting from the Kondo lattice model with the Rashba spin-orbit
coupling, we derive an effective spin model with generalized
Ruderman-Kittel-Kasuya-Yosida interactions including the anisotropic and
antisymmetric exchange interactions. By performing simulated annealing for the
effective model, we find that a vortex crystal of N\'eel type is stabilized
even in the absence of a magnetic field. Moreover, we demonstrate that a
Bloch-type vortex crystal, which is usually associated with the Dresselhaus
spin-orbit coupling, can also be realized in our Rashba-based model. A magnetic
field turns the vortex crystals into N\'eel- and Bloch-type skyrmion-like
crystals. Our results underscore that the interplay between the spin-orbit
coupling and itinerant magnetism brings fertile possibilities of noncoplanar
magnetic orderings.
