Register App as "send to"/"share via" destination

Within my smartphone, I’m missing an option to directly send a PDF to SparkReceipt.
Use cases :

1) From mail client, send directly an attached invoice to Sparkreceipt (would even be faster than on desktop : save then upload)

2) From CamScanner App, send scanned receipt to SparkReceipt (sorry, CamScanner is much more efficient for scanning receipt, and that’s fine for me as long as I can easily pass over PDF)