The RTL design engineer owns the logic of a block or subsystem. Starting from a specification, they define the micro-architecture, write clean Verilog or SystemVerilog, and make sure the design is ready for synthesis, timing and verification.
Day to day, that means writing and reviewing RTL, running lint and clock-domain-crossing checks, working with verification engineers on coverage and bugs, and working with physical design on timing and area. Good RTL engineers think about power, performance and area from the first line of code, and write designs that are easy to verify and integrate.
Because RTL decisions ripple through verification, implementation, test and silicon, the quality of the RTL team shapes the whole schedule. Engineers who have taken designs through tape-out and bring-up are especially valuable.