The technique of embedded coding has been shown to be advantageous compared to conventional ARQ systems which use a single basic code rate. This technique provides a highly reliable method of error correction while maintaining a relatively high average code rate and is therefore suitable for use on time-varying channels such as the HF (3 MHz-30 MHz) skywave channel. The use of Reed-Solomon codes in an embedded scheme is analysed and results are presented verifying the improvement which can be obtained compared to previously reported embedded coding schemes.