The problem here seems to be that it is the G7/D chord that would resolve well to C, but following it with Am and F takes the progression in another direction, and just ending on G7/D, Am, F, C indeed doesn't sound all that final unless you carefully choose the voicing. And also, if the previous part had a repetition of those four chords, there's nothing telling the listener that this part won't just repeat the sequence like it did before.
If you want to avoid ending on C, you could end e.g. on the relative minor Am, with a sequence like G7/D, Am, F, Dm, G, Am, but this will always sound a bit open-ended.
There are options to end on C and make it sound more final. One is to cut the progression short after G7/D and go straight to C. Another would be to follow G7/D, Am, F with another G7/D before going to C; or a variation of that with a straightforward G instead of a G7 (especially when played lower than the first G7/D) or go via Dm to G to C; and maybe give the G7/D or G two measures before resolving on C.
Another interesting option is to follow G7/D, Am, F with an F6/9, and then resolve to C via a combination of G7/D, Dm and/or Bdim. Or a simpler version that just goes from the G7/D, Am, F, to Bdim and then C.