Keynote can't accept postscript or svg files. Postscript is an outdated technology, Adobe has replaced Post Script with PDF. Its best to maintain vector images in Keynote, not replace it with bitmap images.
Here is a list of vector graphic filetypes compatibility with Keynote:
drag and drop PDF files directly onto a Keynote slide
PDF is a native file format for Keynote, imported vector shapes and files are saved as PDF files within Keynote. Its therefore useful to save other graphic file formats to PDF files as Keynote can preserve the vector shapes and maintain resolution of bitmap files.
Illustrator (ai) files
Illustrator files can be drag and dropped using Finder on to the slide
Encapsulated PostScript files(eps)
drag and drop directly on to a Keynote slide
Shapes created in PowerPoint can be directly placed on to a Keynote slide using copy and Paste
Scalable Vector Graphic files (svg) can’t be used in Keynote, convert to PDF then import to Keynote
Postscript files (PS) are unable to be used in Keynote