> How do you scroll the preview window with keyboard ?

    alias pf="fzf --preview='less {}' --bind shift-up:preview-page-up,shift-down:preview-page-down"

That will let you run `pf` to preview files in less and lets you use shift + arrow keys to scroll the preview window. No dependencies are needed except for fzf. If you want to use ripgrep with fzf you can set FZF_DEFAULT_COMMAND to run rg such as `export FZF_DEFAULT_COMMAND="rg ..."` where ... are your preferred rg flags. This full setup is in my dotfiles at https://github.com/nickjj/dotfiles.

I've made a video and blog post about it here: https://nickjanetakis.com/blog/customize-fzf-ctrl-t-binding-...

I also made https://nickjanetakis.com/blog/using-fzf-to-preview-text-fil... which covers how to modify fzf's built in CTRL+t shortcut to allow for previews too. CTRL+t is a hotkey driven way to fuzzy match a list of files.