Many distributions of Vim ship with support for Scheme, which will mostly work for Racket. As of version 7.3.518, Vim detects files with the extension .rkt as having the scheme filetype. Version 8.2.3368 added support for .rktd and .rktl.
In older versions, you can enable filetype detection of Racket files as Scheme with the following:
autocmd filetypedetect BufReadPost *.rkt,*.rktl,*.rktd set filetype=scheme
If your Vim supports the ftdetect system, in which case it’s likely new enough to support Racket already, you can nevertheless put the following in "~/.vim/ftdetect/racket.vim" ("$HOME/vimfiles/ftdetect/racket.vim" on MS-Windows; see :help runtimepath).
" :help ftdetect
" If you want to change the filetype only if one has not been set
autocmd BufRead,BufNewFile *.rkt,*.rktl,*.rktd setfiletype scheme
" If you always want to set this filetype
autocmd BufRead,BufNewFile *.rkt,*.rktl,*.rktd set filetype=scheme
The major difference between the two is that the benknoble/vim-racket fork supports more features out of the box and is updated more frequently.
This approach is more flexible but may lead to more work. Since each #lang has its own filetype, options, syntax highlighting, and other features need to be configured for each filetype. This can be done via the standard ftplugin mechanism. See for example :help ftplugin-overrule and :help ftplugin: place your options for <lang> in "~/.vim/after/ftplugin/<lang>.vim" ("$HOME/vimfiles/after/ftplugin/<lang>.vim" on MS-Windows). Similarly, syntax files follow the standard mechanism documented in :help syntax.
Both plugins come with configuration for Racket (and possibly other #langs) as ftplugins. To enable them, use the :filetype command as documented in :help :filetype. You likely want to turn on filetype plugins (:help :filetype-plugin-on) and filetype indent plugins (:help :filetype-indent-on).
You can enable indentation for Racket by setting both the lisp and autoindent options in Vim. You will want to customize the buffer-local lispwords option to control how special forms are indented. See :help ’lispwords’. Both plugins mentioned in Plugins set this option for you.
However, the indentation can be limited and may not be as complete as what you can get in Emacs. You can also use Dorai Sitaram’s scmindent for better indentation of Racket code. The instructions on how to use the indenter are available on the website.
The Rainbow Parenthesis script for Vim can be useful for more visible parenthesis matching. Syntax highlighting for Scheme is shipped with Vim on many platforms, which will work for the most part with Racket. The vim-racket script provides good default highlighting settings for you.
The Slimv plugin has a paredit mode that works like paredit in Emacs. However, the plugin is not aware of Racket. You can either set Vim to treat Racket as Scheme files or you can modify the paredit script to load on ".rkt" files.
The benknoble/vim-sexp fork is slightly more modern vimscript.
Again, benknoble/scribble.vim is updated more frequently and is somewhat more modern.
If you are installing many Vim plugins (not necessary specific to Racket), we recommend using a plugin that will make loading other plugins easier. There are many plugin managers.
Pathogen is one plugin that does this; using it, you can install new plugins by extracting them to subdirectories in the "bundle" folder of your personal Vim files ("~/.vim" on Unix, "$HOME/vimfiles" on MS-Windows).
With newer Vim versions, you can use the package system (:help packages).
One relatively up-to-date reference on the various managers is What are the differences between the vim plugin managers?. The same site, Vi & Vim is a great place to get help from Vimmers.